C# Dot Net

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Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com 1

C# 2010 with Microsoft.Net

Framework 4.0

Pragati Software Pvt. Ltd.www.pragatisoftware.com

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IndexModule Particulars PageModule 1 Getting Started 4Module 2 Basic Language Constructs 15Module 3 Class and Object 37Module 4 Class Library 47Module 5 Inheritance 59Module 6 Exception Handling 75Module 7 Other C# Features 85Module 8 String, StringBuilder and Dateformats 99Module 9 Collection classes 117

Module 10 Generics and Nullable Types 129Module 11 Windows Form Control I 137Module 12 File I/O 159

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Index (Contd…)

Module 13 Working with DB 181Module 14 Data Bound Controls 226Module 15 DotNet Framework and Assembly 239Module 16 Delegate 244Module 17 Thread 253Module 18 Introduction to Web Services 273APPENDIX Windows Form Control II 290APPENDIX Advance Thread 306APPENDIX Reflection 320APPENDIX Serialization 324

APPENDIX Iterators 332APPENDIX SQL BULK copy 351APPENDIX Database Operations 353

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Module 1: Getting Started

• OverviewIntroduction to C#Types of applicationsUnderstanding some terms: solution, project, Visual Studio IDEWriting, compiling and running a simple program


Framework Version

CLR 4.0

.Net Framework 2.0C# 2.0 VB 8.0

.Net Framework 3.5C# 3.0 VB 9 LINQ AJAX

Enhancement for WCF, WPF, WF

.Net Framework 3.0WCF WPF WF Card Space

.Net Framework 4.0C# 4.0 VB 10 PLINQ MEF

DLR Code Contracts

MEF : The Managed Extensibility Framework or MEF is a library for creating lightweight, extensible applications. It allows application developers to discover and use extensions with no configuration required. It also lets extension developers easily encapsulate code and avoid fragile hard dependencies. MEF not only allows extensions to be reused within applications, but across applications as well.

DLR : The dynamic language runtime (DLR) is a runtime environment that adds a set of services for dynamic languages to the common language runtime (CLR). The DLR makes it easier to develop dynamic languages to run on the .NET Framework and to add dynamic features to statically typed languages.


.Net Framework

.NET Framework is a common platform for designing, developing and deploying the various types of applications such as:

Console Application, Windows Application, Web Based Application, Class Library Application, Web services, WCF, WPF, WF etc..

A developer can develop application by using any of the language which is compatible with .NET Framework. The languages compatible with .NET Framework are such as C#, VB, J#, VC++, F# etc.

The Base class library provides a comprehensive set of facilities for application development.

The .NET Framework provides a run-time environment called the Common Language Runtime. It runs thecode and provides the services which makes the development process easier.

Microsoft provides IDE as a Visual Studio to implement the .NET Framework.

.NET Framework comes with redistributable installer that contains the Common Language Runtime and .NET Framework components which are necessary to run .NET Framework applications.The .NET Framework is available as a stand-alone executable file, Dotnetfx.exe.

NOTE:Prior to .NET Framework for developing different types of applications different technologies were used.E.g. : For developing Console applications languages such as C/C++ was used.For developing Windows based applications VB was introduced by the Microsoft.For developing and designing web based applications, technologies such as HTML, DHTML, JavaScript, classic ASP were used.It means for developing specific type of application, one has to use different technologies.

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Types of Applications

• Console applications. • Windows applications • ASP.NET Web applications• Class libraries • Custom controls (User defined controls). • Windows service• Web Service

We can create multiple kinds of applications such as:Console Applications:

Applications that run on command prompt.Windows Applications:

Desktop application using windows forms.ASP. Net Web Applications:

Browser based applications i.e. Web sites.Class Library:

Components basically are reusable piece of code that contains some business logic.Custom Controls:

We can create our own controls from the existing controls either in windows or in web.Windows Services:

We can create services that run in the background.Web Services:

Web Services are web components. We can have a business logic available on the web that can be shared by people across the world.

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Features of C#

• Object-oriented features• Structured exception handling • Powerful Windows based applications• Building Web based applications• Simple data access• Multithreading• Simplified deployment• XML Web Services

Features of C#C# is a very powerful language. It implements Rapid Application Development Tools for

developing various kinds of application. Full Support for Object Oriented Programming.Structured Exception Handling helps create and maintain the program with robust error

handlers. In this technique, we write a code which detects and traps the errors during execution and prevents application from inconsistent state.

.NET provides an IDE to develop all kinds of applications such as Windows, Web, Console, AJAX based, Mobile etc into one environment using the languages that are supported by framework.

Multithreading Capabilities.

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Creating a New Project (Contd...)

2.Language

1. Framework Version

3. Application Template

4. Project Name

5. Project Location

6. Solution Name

Start Microsoft Visual Studio 2010.Click on File > New > Projects 1.Select from the drop down appropriate version of .NET Framework.2.Choose the language C# from Left hand side project type..3.On the right hand side from the templates available, select Console Application.4.Specify the project name.5.Select the location to save the project.6.Specify the name for solution.

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Solutions and Projects

• A solution usually acts as a container for one or more projects

• A project typically contains all the files required for the application.

1. Solution name

2. Project name

1. Solutions:A Visual Studio solution can include just one project or several projects built jointly by a

development team. A complex application might require multiple solutions. 2. Projects:

Visual Studio projects are used as containers within a solution to logically manage, build, and debug the items that comprise your application. The output of a project is usually an executable program (.exe) or a dynamic-link library (.dll) which known as Assembly.

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Writing the First Program

• Click on Debug -> Start to view the output.

namespace Module01{

class Program{

static void Main(string[] args){

Console.WriteLine("Hello World...");Console.ReadLine();

}}

}

(Source code: C:\Training\Module01\Module01\Module01\Program.cs)

Namespace is a logical collection of the types such as:classinterfacestructenumdelegate

In class Program we have Main() method which is known as entry point.Console is a class under System namespace which has a WriteLine() and ReadLine() as a method.


Compilation Process in .NET

Visual Basic C# J#

Compiler

CPU CPU

JIT JIT

Windows CLR MAC CLR

Managed code

Compiler Compiler

.Net framework supports various languages to develop the applications. A developer may write a code by using any of the language (VB, C#, J#, VC++, F#) which is compatible with .Net Framework. What happens when the code is written and compiled in .Net framework?Every language has its own language compiler. Very first the code is compiled by the language compiler and it produces a MSIL (Microsoft Intermediate Language) code. It is also known as “IL” code.This MSIL code is now sent to the CLR (Common Language Runtime).Once the MSIL code is sent to the CLR, only the code which is required during runtime is getting compiled into native machine code. This process is known as “JITing” and it is performed by a component known as “JITer” (Just in Time Compiler).Once the native machine code is produced it goes through under tight security policy which is known as “CASPOL” (Code-Access-Security-Policy). If this code is safe then only it is executed on CPU. This code is also known as “managed code”.

Same process happens for the other OS also.

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Location of .exe file.

1. Location of .exe

2. Exe file

.Exe is always stored at location : project folder\bin\debug.

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Components of CLR

Class Loader : It loads all the Base Class Libraries required during execution of code.Type Verifier : Type verifier checks for the type compatibility. It is also known as “CTS”(Common Type System). The specification for the types are specified by “CLS” (Common Language Specification).Exception Manager : Exception manager manages the exception during runtime.JIT : Just-In-Time compiler produces native machine code which is required while runtime.Garbage Collector : It is also known as “Heap Manager” or “Auto memory manager”. It releases the memory by removing unused/out of scope objects. In invokes automatically. One can not predict about it’s invocation.Security Manager : Once the native machine code is produced, it is sent to the CPU for execution. This native machine code goes under tight security policy. This security policy is known as “CASPOL” . It is categorized into : 1) Code based Interface 2) Role based Interface.Thread Manager : Thread manager manages the multi-threading envt.COM Marshaller : While migrating from old COM application to .NET application ,the type compatibilty of COM applications with .NET types is marshalled by this component.

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Module 2. Basic Language Constructs

• OverviewVariables and data typesOperators (arithmetic, relational, logical, assignment, conditional, etc.)Conditional statements

• if – else• switch

Looping Constructs

• while• do….loop while()• for

Arrays


Data Types (Contd…)

The .NET platform provides Common Type System to all the supported languages. This means that all the languages must support the same data types as enforced by common language runtime.

Data Types Description Exampleobject The ultimate base type of all other types object o = null;string String type; a string is a sequence of Unicode characters string s = "hello";sbyte 8-bit signed integral type sbyte val = 12;short 16-bit signed integral type short val =12;int 32-bit signed integral type int val=12;long 64-bit signed integral type long val1=12; long val2=34L;byte 8-bit unsigned integral type byte val1=12;ushort 16-bit unsigned integral ushort val1=12;uint 32-bit unsigned integral type uint val1=12; unit val2=34U;ulong 64-bit unsigned integral type ulong val1=12; float Single=precision floating point float val = 1.23f;double Double-precision floating point type double val1=1.23; double val2=4.56D;bool Boolean type; a bool value is either true or false bool val1=true;char Character type; a char value is a Unicode character char val1=‘h’;decimal Precise decimal type with 28 significant digits decimal val = 1.23M;

Formatting Numeric DataC or c – Currency formatD or d – doubleM or m – decimalF or f – floatL or l - long 16

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Variable and Data type Program

static void Main(string[ ] args) {double centigrade;double fahrenheit;centigrade = 33.3;fahrenheit = (centigrade * 9 / 5) + 32;Console.WriteLine("33.3 Centigrade = " + fahrenheit + " Fahrenheit.");Console.ReadLine();

}

(Source code: Module02\Module02\01variable.cs)Variable Declarationint num;double salary, balance;string name;


Common Type System (CTS)

Visual Basic.NET

CLS

C#VC++

Common Type System

The Common Type System , is a part of the .net framework describes how the various data types must be declared, managed and used at runtime and plays a very crucial role for supporting cross language integration. Some of the most common functions it conducts are :1.Type Safety, Cross language integration and high performance execution of code.2.It has a set of rules that all .net compliant languages must follow so that the objects created in those languages can interact with each other . It supports the complete implementation of the programming languages.Common Language Specification (CLS) :

When you write code in one language and this code is then used by other programs that were developed in different languages, then that code should be CLS compliant, which simply means that it should abide by the rules specified in the CLS. The CLS describes features such as common data types for different languages. CLS compliance is important when software components that are created in one language will be used by other languages. The CLS is called as a subset of the CTS because it defines those set of rules that are a part of the CTS itself.

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CLS

C#int i;

string str; double dbl;

VB.NETDim i as IntegerDim str as String

Dim dbl as double

.NET TypeSystem.Int32 i;

System.String str;System.Double dbl;

If one application written in C# and one application written in VB.NET wants to communicate with each other, how the communication will happen?In .NET if C# uses int to store numeric value which has a storage size 32 bits and VB.NET uses Integer to store numeric value which also has a storage size 32 bits. Then Common language specification specifies the common type compatible with both the types and produces a result as Int32.

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Named Constant

static void Main(string[ ] args) {const float Pi = 3.14f;float radius, area;radius = 10.0f;area = Pi * radius * radius;Console.WriteLine("Area of circle = " + area.ToString());Console.ReadLine();

}

(Source code: Module02\Module02\02constant.cs)

Named constants are created by declaring a variable with keyword const.

Using a named constant can improve the readability of your code, as it becomes a form of documentation. Besides, since a named constant is defined in only one place in a program, if the value of the constant needs to be changed, it needs to be changed only in one place. Thus, use of named constants improves program maintenance also.

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Writing comments

static void Main(string[ ] args){

/* variable declaration */const float Pi = 3.14f;float Radius, Area;Radius = 10.0f;/* Calculation */Area = Pi * Radius * Radius;//Printing ResultConsole.WriteLine("Area of circle = " + Area.ToString());Console.ReadLine();

}

Comment

comments can improve the readability (and thereby, maintainability) of source code.

Single Line comment

//

text following // up to the end of the line is treated as a single line comment, and is ignored by the compiler.

/*

*/

Similarly, any text between /* and the next */ is known as multi line comment, and is also ignored by the compiler.

In C# you can add the contents by using short-cut keys (ctrl+E, C). And for uncommenting short-cut key used is (ctrl_E, U).

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Taking Input from the User


const float Pi = 3.14f;float Radius, Area;Console.Write("Enter the value for radius : ");Radius = float.Parse (Console.ReadLine());Area = Pi * Radius * Radius;Console.WriteLine("Area = " + Area.ToString());Console.ReadLine();

}

Input window

Output window

(Source code: (Source code: Module02\Module02\03userinput.cs)

To take input from the user at the runtime we use Console.ReadLine() method and assigning the value to the variable “Radius”.

When we take the input from the command line it is always taken as string type. The data type of the Radius variable is float, so we require to convert string type to float type. For that we are using the method Parse of the float type to convert string value to the float value.

When we print the value we are giving message and then we display the value. So every part of the Console.WriteLine() method has to be of a string type. So for printing we are converting the decimal value of area into string by using ToString() method.

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Operators

Operator Language Element

Arithmetic +, –, *, /, %

Unary ++ , --

Assignment =, +=, -=, *=, /=

Comparison ==, !=, <, >, <=, >=

Concatenation +

Logical operations &&, ||

e.g. int num1=5, num2=10, num3;Arithmetic Operators : num1 + num2; num1 – num2; num1 * num2 ; num1 / num2; num1 % num2;Unary : pre-Increment/pre-decrement : ++num1 / --num1;

post-Increment/post-decrement : num2++/num2 --Assignment : num3=num1 + num2; num1+=num2;Comparison : num3= num1==num2; It will return 1 (true) if both the numbers are equal or 0 (false) if numbers not equal.Concatenation : string str1 = “Hello “, str2 = “World”; Console.WriteLine(str1 + str2); Logical operations : && (Logical and) :num3=(num1 >5 && num2<=10); It will match both the expression. If both the expressions are true it will return 1 otherwise 0 for false.|| (Logical or) : num3=(num1 > 5 || num2<=10); It will return 1 (true) if any one of the expression is matched.

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The if...else Structure

if (expression)statement;

if (expression)statement1;

elsestatement2;

if (expression)statement1;

else if (expression)statement2;

elsestatement3;

if (expression){

statement1;if (expression)

statement2;}else

statement3;

If-else is a decision making statement. Returns true if the condition is true or returns false in else part.


The if...else Structure Example


int Num1 = 10, Num2=15;if (Num1 > Num2)

Console.WriteLine("Num1 is greater the Num2");else

Console.WriteLine("Num2 is greater then Num1");Console.ReadLine();

}

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The multiple if Structure Examplestatic void Main(string[] args)

{int a = 5, b = 6, c = 7, min, max;if (a >= b){

if (a >= c){ max = a;

if (b >= c){ min = c; }else { min = b; }

}else{ max = c; min = b; }

}else if (b >= c){ max = b;

if (a >= c){ min = c; }

else { min = a; }

}else { max = c;

if (a >= b){ min = b; }else { min = a; }

}Console.WriteLine("max={0} min={1}", max, min);

}

(Source code: Module02\Module02\04if.cs)

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The switch statement

switch (expression){

case value:statements;break;

case value:statements;break;

default:statements;break;

}

To choose one option among the multiple choices switch-case statement is used.

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The switch statement Examplestatic void Main(string[] args){

int month = 1;switch (month){

case 11:case 12:case 1:case 2:

Console.WriteLine("Winter Season");break;


Console.WriteLine("Summer season");break;


Console.WriteLine("Monsoonseason");

break;default:

Console.WriteLine(“Invalid month);

} }

(Source code: Module02\Module02\06switch.cs)

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while loop


int num = 1;while (num <= 5){

Console.WriteLine("Number = " + num.ToString());num++;

}Console.ReadLine();

}

while (condition) {statements;increment / decrement

statement}

(Source code: Module02\Module02\07while.cs)While loop:

The boolean expression is evaluated, and if true, the following statement (which can be a block) is executed. Thereafter the boolean expression is evaluated again, and once again, if true, the following statement is executed. This process continues until the boolean expression evaluates to false.

A while loop does not execute at all if the boolean - expression is false the first time itself. If you want a loop to be executed at least once before checking the boolean - expression, you should use the do...while loop.

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do…while Example


int num = 0;do{

Console.WriteLine("Number = " + num.ToString());num+=2;

} while(num<=10);Console.ReadLine();

}

do{

statements;increment / decrement statement

} while (condition);

(Source code: Module02\Module02\08doloop.cs)

Here the boolean expression is evaluated after executing the statement. While the expression is true, the statement is executed repeatedly.

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for (initialize; condition; increment/decrement){

statements;}

For Loop


for (int number = 101; number <= 105; number++){

Console.WriteLine("Number = " + number);}Console.ReadLine();

}

(Source code: Module02\Module02\09for.cs)

For loop is used for fixed iteration.

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Array

• Array is a group of elements having same name, same data type and different index.

stack

heap

An array is an ordered collection of elements. Elements of an array can be of primitive types or references to objects.

The value defined in the square bracket is the size of the array. Lower limit start with zero (0)Upper limit is whatever is the size -1.

The first element of the array has index zero, and the index of the last element is one less than the length of the array. Thus, the first element of the above array is referred to as numbers [0], while the last element is numbers [4]. The length of an array is available with the length field.

Stack memory : All value types are primarily stored on stack area.Heap memory : All reference types are stored on heap area.


Array (continued…)

• int [ ] numbers = new int[5];Or

int [ ] numbers = new int [ ] {10,20,30,40,50};

Orint [ ] numbers ={1,2,3,4,5};

1-D Array

ReferenceArray Object

10 20 30 40 50

Syntax:-Datatype [ ] arrayname = new Datatype [size];

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As every string itself is an object, array of strings is nothing but array of references to string objects.


Memory Map of array (contd…)

String [ ] zones = { "East", "West", "North", "South“ } ;

1-D Array

North


East South West

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Array class and methods

Method Explaination Syntax ExampleReverse() Revereses the

order of array elements.

Array.Reverse(array); int [] numbers =new int{24,12,3,43,43};Array.Reverse(numbers);

Sort() Sorts array in ascending order.

Array.Sort(array); Array.Sort(numbers);

Clear() Sets the range of elements in the array to zero, or to false, or to Nothing depending on the type of array

Clear(Arrayname,int,int) Array.Clear(numbers,0,5);

Array class is the base class for all the arrays in CLR.

(Source code: Module02\Module02\10Array.cs)

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Multidimensional Array

int[,] number = new int[3,3];number [0,0]= 10;number[0,1] = 20;Orint[,] num = new int[,] { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };

2-D Array


1 2 3 4 5 6

SyntaxDatatype [,] arrayname = new Datatype [rows, columns];

(Source code: Module02\Module02\11MultidimensionArray.cs)Multi dimensional arrays are always the collection of One dimensional arrays. One 1-D array for each row and one 1-D array of references to preserve references to the 1-D arrays which are carrying values.

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Module 3: Classes and Objects

• OverviewClasses and ObjectsFields and MethodsAccess ControlThe “this” referenceConstructorsOverloadingPropertiesStatic Methods and Fields

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Classes and Objects

• ObjectAn object is an instance of the class. It is a real time entity.A class does not have its own existence (memory allocation), objects created for those classes do. For this reason, objects are said to be an instance of a class. For e.g. Apple is an object of fruit class or car is an object of vehicle class.Each object has an attribute and behaviour. Attribute defines physical presentation of object and behaviour defines the tasks which the object can perform.

• ClassA class can be considered as a generalized description of one or more objects that share the same set of attributes and responsibilities. A class is known as a user defined data type.


Classes and Objects Continued…

Object Class Attributes Behaviourcar Vehicle Wheels, Engine,

HeadlightsSpeed(),

john (Emp) Employee Empid, Empname, Salary

CalcBonus()

bankAccoutntObj BankAccount Accno, Accname, Balance

Deposit(),Withdraw()

smith Student Name,Address,Semester

Get Result()

coffee Product ProductId, Productname, Quanity, Price

CalcTotalPrice()

An object is anything that is of some interest to an application under development. An object may represent some real-life entity, or an event, or some aspect of the solution strategy to a given business problem. In a banking application, an accountholder (or its data representation within the system) is an object. In a sales information system, a product is an object. In a library management system, students, faculty members, books are all objects.

Objects have attributes; these are characteristics that describe the objects. For example, a student object may have the attributes such as name, address, semester, etc. A book object may have the attributes such as book ID, title, author, publisher, etc.

While talking about objects, we cannot ignore talking about classes. A class can be considered as a generalized description of one or more objects that share the same set of attributes and responsibilities. For example, all employees belong to an Employee class.

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Classes and Objects

Rectangle Class

CalcPerimeter()CalcArea()

length=5 width=8

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Creating a Rectangle Classclass Rectangle

{float length=5;float breadth=8;public float CalcArea() {

return length * breadth;}

public float CalcPerimeter() {return 2 * (length + breadth);

}}static void Main(string[] args)

{ //Class InstantiationRectangle rectangleObject = new Rectangle();Console.WriteLine(“Area={0}”,rectangleObject.CalcArea().ToString());Console.WriteLine(“Perimeter={0}”,rectangleObject.CalcPerimeter().ToString()); Console.ReadLine();

}

(Source code: Module03\SimpleClassObjectDemo\Rectangle.cs)

A class may have zero, one or more fields; these are variables that hold data for an object of that class. The Rectangle class above has two fields: length, breadth. Every object of this class has its own specific instances of these variables.

A class's methods contain the code that understands and manipulates the state of an object. The Rectangle class has various methods, such as CalcArea(), CalcPerimeter(). These methods modify or return some fields of the class.

The code has one more class called Program, in the main method of which one object of the Rectangle class is created and used. All these aspects are explained in subsequently.

In the above example the Rectangle class is instantiated using the “new" keyword. The "rectangleObject" is the object reference which holds the Rectangle’s object. Using this reference the CalcArea() and CalcPerimeter() method is invoked through which the data is set.


Properties • In the previous example the values are assigned in the class

itself. • What if one wants to get input from the user?

It’s not possible at this point of time. Because in C# by default class members are private. Hence the fields length and breadth are private. Private fields are not accessible from outside of the class.

• C#.NET provides us solution for this as Properties.

(Source code: Module03\SimpleClassObjectDemo\RectangleVersion3.cs)

You can use both fields and properties to store information in an object. Although public fields and properties are almost indistinguishable from a client-application perspective, they are declared differently within a class. Whereas fields are simply public variables that a class exposes, properties use methods to control how values are set or returned.

Properties have get and set accessor.Get accessor is used to return the value of a property Set accessor is used to set the value of a property; they have a parameter, usually called Value, with the same data type as the property itself.

Property can be declare as ReadOnly or WriteOnly which help us to keep check on the variable.

ReadOnly property allows only reading value of the variable. We can not change the value of the variable. Only have “get” accessor.

WriteOnly property allows only setting value for the variable. We can not able to read the value from the variable. Only have “set” accessor.

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Properties (continued…)

//propertyprivate float length;public float Length {

get { return length; }set { length = value; }

}private float breadth;public float Breadth {…}

Private field

Private field

static void Main(string[] args){Rectangle rectangleObject1 = new Rectangle();rectangleObject1.Length = 5;rectangleObject1.Breadth = 8;

Console.WriteLine(“Area={0}”,rectangleObject1.CalcArea().ToString());Console.WriteLine(“Perimeter={0}”, rectangleObject1.CalcPerimeter().ToString()); Console.ReadLine();}

In the above code length and breadth are the private fields, hence can not be access from outside. Therefore public properties are defined for those private fields. It has get and set access specifiers. get returns the value and set assigns the to a field.

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Constructors

•Constructor is a special method which has same name as class.•Constructor is invoked when the class is instantiated.•Constructor method does not have any return type.

class Rectangle {float length;float breadth;//constructorpublic Rectangle() {

length = 0;breadth = 0;

}}

static void Main(string[] args){

Rectangle rectangleObject1 = new Rectangle();…;} Instance creation

Constructor invoked

Constructorsis a special method that is executed when an object of the class is to be created. A

constructor is typically used to initialize the state of an object.

A constructor is a special method that must be present in a class for the class to get instantiated. Constructor is having the same name as of the class. When there is no constructor present, .NET Framework will create one for you. When you instantiate an object by using the new keyword, the class's constructor is called. You can provide initialization code that is guaranteed to run when the object is instantiated. If you write a constructor explicitly in your class, .NET Framework won't create it anymore.

Like other methods, a constructor can take parameters, but cannot return a value.

The constructor of a class can never be explicitly called; it is automatically called when an object of the class is created by you.

For every new instance the constructor is going to be called.

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Constructor Overloading

class RectangleVersion2{float length;float breadth;

//constructorpublic RectangleVersion2() {

this.length = 0;this.breadth = 0; }

public RectangleVersion2(float _length, float _breadth)

{this.length = _length;this.breadth = _breadth;

}}

static void Main(string[ ] args) {RectangleVersion2 rectangleObject1 =

new RectangleVersion2();

RectangleVersion2 rectangleObject2 = new RectangleVersion2(8, 6);

Console.ReadLine();

}


A class can have two or more different methods (constructor, methods) with the same name, provided their signature is different. The signature of a method is• The Name of the method• Number of Parameters• Types of Parameters• Order of Parameter

This feature of having multiple methods with the same name but different signatures is known as overloading. When you call a method, the compiler determines the actual method to invoke based on the number and types of parameters supplied by you.However it is not overloaded by varying only one or more of the following items• The modifiers such as public, shared, static• The Parameter name• The Parameter modifiers, such as ref and out• The data type of the return value

Static constructor cannot be overloaded. We can only overload instance constructor.

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The “this” Reference

public RectangleVersion2(){

this.length = 0;this.breadth = 0;

}


A method of an object can refer to itself by using the “this” reference. One common use of the this reference is when you need to pass a reference to the current object to some other method. The this reference is also often used when the name of some parameter is the same as the name of a data member.


Module 4: Class Library

• Overview Overview of Class LibraryCreate Class Library.Create a Test Application.


Overview of Class Library

• The .NET framework is a collection of Base Class Libraries. E.g :- System, System.IO etc.

• As per business requirement you can create your own library and use it in one or more applications.

• A library is a reusable component which has an extension .dllwhich needs to be referenced from the executables.

.dll

UI Application


Create Class Library

1. Start Microsoft Visual studio 2010 New Project.2. From the project types select Class Library. 3. Name it as HRSystem.

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Create Class Librarypublic class Employee {private int empId;private string empName;private double salary;

public Employee() {… }public Employee(int id,string Name, double sal)

{this.empId = id;this.empName = Name;this.salary = sal;}

//properties....

public double CalcBonus(double percentage){

return salary * percentage;}

}

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Creating Class Library continued…

• Build EmployeeLibrary. • It will generate .DLL file.

Menu options for building project:1. Click on Build Menu -> Build EmployeeLibrary.

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Create a Test Application

1. Add a new Console Application in the same solution.2. Save it as ABCCorporation.3. Add reference to ABCCorporation project.

Menu option for adding the project:1. File -> New Project -> Console Application.2. Save as ABCCorporation.3. From the solutions drop-down list select -> Add to Solution.

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Adding reference of dll to Application

Menu options:1.Click on Project -> Add reference .2.From the dialogue box select projects tab -> select EmployeeLibrary.dll. (It the dlland application is in the same solution otherwise click on browse tab and select the required dll from the path).

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Creating a Test Applicationusing EmployeeLibrary;class Program

{static void Main(string[] args){

Employee employee = new Employee(1,"Trupti", 25000);double bonus=employee.CalcBonus(0.3);Console.WriteLine(“Bonus={0}”,bonus);Console.ReadLine();

}}

(Source code : C:\Training\Module04\EmployeeLibrary\ABCCorporation\Program.cs)

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Set startup project

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Static field

• Static field is used when we want to have values that are shared across all instances of a particular class.

• Static fields and static constants enable this to happen by belonging to the class and not to the actual objects.

• In your application, you can declare a variable and refer to it regardless of which instance of an object you are using. Such a variable is called static.

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Static fieldpublic class Employee

{……private static int Id=0;

public Employee() {empId = 0;empName =“unknown”;salary = 0; }

public Employee(int id,string Name, double sal){

++id;this.empId = id;……}


Assignment • Create a class library project. Add Product class with

following members:

Product-productId ;-productName ;-unitPrice ;-Quantity

+ GetProducts(productname,unitprice,Quantity);

• productId must me auto incremented.• Display totalprice of product available

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Module 5. Inheritance

• OverviewObject Oriented ConceptsBank Case StudyInheritanceConstructor in extended classesOverriding methodsPolymorphismUse of Sealed keywordAbstract class and methodDeclaring InterfaceImplementing Interface

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Object Oriented Concepts

• Abstraction• Encapsulation• Inheritance• Polymorphism

Abstraction refers to the description of externally visible behavior of an object. Abstraction is used to describe what an object does, rather than how it does it.

Encapsulation is a description of the internal data structures and internal implementation that give rise to this externally visible behavior. Encapsulation deals with how the object does it.

Inheritance facilitates reusability of code. A new class can inherit all the properties and methods of another existing class.

Polymorphism refers to the ability to hide many implementations behind the common interface. Using polymorphism, a single name may denote objects of many different classes.


Bank Application

• Create a class library project.• Save it as BankLibrary.• It will provide Business Logic of Banking Services.

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A BankAccount Class – the Super Classpublic class BankAccount {

…. ;public BankAccount() {

….;}

public BankAccount (string AccName, double Balance) {

…. ;}

public int AccNumber { get ; }public string AccName { get ; set ; }public double Balance { get ; set ; }

public double Withdraw(double amount) {…..; }

public double Deposit(double amount) {….. ; }

}

(Source code: C:\Training\Module05\BankLibrary\BankLibrary\BankAccount.cs)

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Inheritance Inheritance is a powerful feature of OOP. It provides following features:

•Reusability •Easy maintenance of code.•Extendibility

InheritanceInheritance is a powerful feature of object-oriented programming languages. This refers to the ability of a class to inherit the fields and operations of another class, and extend these further.

Inheritance can also be useful when two or more classes have some fields and operations in common. Instead of duplicating these common aspects in various classes, we can keep them in a base class, that other classes inherit from.

For example, in a banking application, we may have a SavingsAccount class as well as a CurrentAccount class. Both these classes may have some common operations and fields, in addition to having their own specific fields and operations. Such common fields and operations can be kept in a common base class called BankAccount. The SavingsAccount and CurrentAccount classes can then inherit from the BankAccount class.

In .NET, there is a class called Object. Every other class explicitly or implicitly inherits from the Object class.

.Net allows single inheritance of the class.


Access Specifiers

Visibility / Access Specifier

private protected internal public protected internal

Same class Yes Yes Yes Yes YesDerived class in same assembly No Yes Yes Yes Yes

Other class No No Yes Yes Yes

Other class in other assembly No No No Yes No

Derived class in other assembly No No No Yes No

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The SavingsAccount Class – the Sub Classpublic class SavingsAccount : BankAccount {

….;static SavingsAccount() {

…. ; }

public SavingsAccount(string AccName,double Balance,bool IsSalaryAccount) :base(AccName,Balance) { ….. ; }

public double CalculateInterest() { …. ; }}

Using Derived class objectstatic void Main(string[ ] args) {

SavingsAccount savingobject = new SavingsAccount();…. ;}

(Source code: Module04\Inheritance\SavingAccount.cs)

An object of the SavingsAccount class would have all the fields other then private of its base class as well as the ones additionally defined within that class. Similarly, on an object of the SavingsAccountclass, all the public and internal operations of the BankAccount class can be applied.

In this program we have created the instance of SavingsAccount class, which is the derived class of the BankAccount class. All the members of the BankAccount class are created inside the memory of the SavingsAccount instance. It is calling the methods inherited from its base as well as of its own.

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Calling parent class constructor class BankAccount {

public BankAccount(float balance) {…. ;

}}class SavingsAccount : BankAccount {

public SavingsAccount(float balance, bool IsSalaryAccount) : base(balance) { .. }}

Object

BankAccount

SavingsAccount

(Source code: Module04\Inheritance\BankAccount.cs)(Source code: Module04\Inheritance\SavingAccount.cs)(Source code: Module04\Inheritance\Program.cs)

A derived class must choose one of its super class constructors to invoke. The part of the object that is inherited from a super class must be initialized properly by the super class itself.

The constructor of a derived class can invoke a base class's constructor using base keyword

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Overriding Methods•A method in sub class with the same signature as a super class has but with different implementation is known as method overriding.

•Same signature means methods must have same name.same number of argumentssame type of arguments.same access specifier

•Keyword virtual is used in base class method definition.

•Virtual indicates that this method can be overriden by sub class.

A subclass can replace its super class's implementation of a method with one of its own. This is known as overriding a method. Both the signature and return type must be the same as the super class.

In .Net by default method of super class cannot be overridden by sub class. For this sub class require permission from the super class

Super class method should have keyword virtual and sub class method should have keyword override.

virtual indicates that this method can be overridden by an identically named method in a derived class. virtual is the default setting for a method that itself overrides a base class method.

Override keyword specifies that a property or method overrides a member inherited from a base class. This keyword indicates that method overrides an identically named method in a base class. The number and data types of the arguments, and the data type of the return value, must exactly match those of the base class procedure.

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Overriding Methods continued…class BankAccount {

public virtual void Withdraw(float amount) { …. ; }}

class SavingsAccount : BankAccount {public override void Withdraw(float amount) { ….. ; }public override ToString() { …. ; }

}

(Source code: Module04\Inheritance\BankAccount.cs)(Source code: Module04\Inheritance\SavingAccount.cs)(Source code: Module04\Inheritance\Program.cs)


Polymorphism

• Polymorphism is a Greek word which means “many-shaped”.• It has two distinct aspects:

At run time object of inherited class may be treated as object of base class .Base classes may define and implement virtual methods and inherited classes may override these methods , which means inherited classes provide its own definition and implementation.

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Polymorphismclass BankAccount {

….. ;public int AccountNumber { ….. ; } public float Balance { ….. ; }public BankAccount() { ….. ; }public BankAccount(float _balance) {

….. ; }public void Deposit(float amount) {

….. ; }public virtual void Withdraw(float

amount) { … ; }}class SavingsAccount : BankAccount{ ….. ;

static SavingsAccount() { …. ;}public SavingsAccount() { ….. ; } public SavingsAccount(float balance,

bool IsSalaryAccount) : base(balance) { ….. ; }

public float CalculateInterest() { ….. ; }public override void Withdraw(float amount)

{ …. ; }}class CurrentAccount : BankAccount {

…… ; public CurrentAccount(float balance, float

overdraftlimit) : base(balance) { ….. ; }public override void Withdraw(float

amount) { ….. ; } }

static void Main(string[ ] args) {BankAccount Bankref;Bankref = new SavingsAccount(7000,true);Bankref = new CurrentAccount(4000,

2000);}

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Preventing Overriding

class BankAccount {public virtual void Withdraw(float amount){ …. ; }

}

class SavingsAccount : BankAccount {public sealed override void Withdraw(float amount){

….. ; }}

(Source code: Module04\SealedExample\BankAccount.cs)(Source code: Module04\SealedExample\SavingAccount.cs)(Source code: Module04\SealedExample\SubSavingAccount.cs)

You can prevent subclasses from overriding the implementation of a method of a super class, by making it sealed.

You can even make an entire class sealed, thereby preventing any extension of that class. All the methods of a sealed class are implicitly sealed.

It can improve security. If a class is sealed, you know that nobody can extend it, and therefore, nobody can violate its contract. Similarly, if a method is sealed, you can rely on its implementation details.

sealed is the default setting for a method that does not itself override a base class method.

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Preventing Inheritance

sealed class SavingsAccount : BankAccount{}

class SubSaving : SavingsAccount // compile time error{}

Sealed classes are primarily used to prevent the inheritance. A sealed class can not be a base class. But it can be instantiated.

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Abstract Class

•The abstract keyword enables you to create classes and class members solely for the purpose of inheritance.

•The purpose of an abstract class is to provide a common definition of a base class that multiple derived classes can share.

•An abstract class can not be instantiated.

public abstract class BankAccount{

public abstract void Withdraw(float amount);}

Abstract class

Abstract method

You can mark a class as abstract, which means that the class cannot be instantiated. This way you can create a class that cannot have objects, but serves as a base for other subclasses.

For example in a bank we can have account as either saving or current but we cannot have account type as a bank.The use of this class would be only to extend it to SavingsAccount and BankAccount class for reducing duplication of work and maintenance.

The opposite of abstract is concrete; a concrete class can be instantiated. For example, Clerk, Executive and Manager would be concrete classes, extending the Employee class.

For example, SavingsAccount and CurrentAccount would be concrete classes, extending the BankAccount.

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Interface

•An interface contains only the signature of methods, delegates and events.•The implementation of the methods is done in the class which implements the interface.•An interface can inherit from one or more base interface.

public interface Iinterest{

float CaclulateInterest(float irate);}

class SavingAccount : BankAccount, Iinterest {public float CaclulateInterest(float irate) {

…. ; }

}

Method signature

Interface implementation

An interface is a way to declare a type consisting only of abstract methods, Events or Properties. An interface provides a protocol binding to the classes that implement it.

An interface cannot be instantiated. It consists of abstract methods, Events or Properties, i.e., it does not contain any implementation. An interface also cannot contain any variables.

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Module 6. Exceptions Handling

• OverviewWhat is Exception Handling?The “try-catch” StructureThe finally ClauseThe throw CauseUser Defined Exception


What is an Exception Handling?

• Error which occurs during runtime is known as Exception.• The mechanism to handle such errors during runtime is called

as Exception Handling.


try-catch-finally

• C# provides 3 keywords to handle an Exception.try :- The try keyword is required. It lets the compiler know that youare attempting a normal flow of a program.catch :-During runtime if any exception occurs instead of letting the program crash the flow of the program can be transferred to cache section. catch block is always followed by try.finally :- This block executes always. It is optional to use finally.

• Syntax for try-catch-finally

try{ error prone code; }catch{ statement for exception handling ; }finally{ statement for clean up ; }

Structured Exception Handling concept is introduced in .NET Framework. The System.Exception is the base class for all the exceptions in .NET. C# provides three keywords try, catch and finally to do exception handling. The try keyword encloses the statements that might throw an exception whereas the catch keyword is used to handle an exception if one exists. The finally clause can be used for doing any clean up process

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Understanding Exceptionsstatic void Main(string[ ] args)

{int num1, num2, ans;num1 = 10;num2 = 0;ans = num1 / num2;Console.WriteLine("Answer = " + ans);Console.ReadLine();

}

Exception occurs here

There are three types of errors which occurs in program, Syntax errors, run-time errors and logical errors. Exception handling is mechanism to detect and handle run time errors.

.NET provides us Exception Handling techniques to overcome such situations.

There are two types of exceptions: System Exception - Exceptions generated by CLR.Application Exception - Exceptions generated in application

When we run the above code, it will get compile but at run time when control come to the line “ans = num1 \ num2", it will throw an exception. We require to manage this type of error which is known as Exception Handling

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Exception Handling Mechanism

static void Main(string[ ] args) {…. ;try {

int num1, num2, ans;num1 = 10;num2 = 0;ans = num1 / num2;

Console.WriteLine("Answer = " + ans);}

catch (DivideByZeroException ex) {Console.WriteLine(ex.Message);

}}

(Source code: Module05\ExceptionHandling\ExceptionHandling\Program1.cs)

If any exception occurs inside the try block, the control transfers to the appropriate catch block and later to the finally block. The try block can exist either with one or more catch blocks or a finally block or with both catch and finally blocks. If there is no exception occurred inside the try block, the control directly transfers to finally block. The statements inside the finally block is executed always.

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Multiple Catch Blockint num1, ans;int[ ] numarray = new int[1];try {

num1 = 10;numarray[0] = 5;ans = num1 / numarray[1];Console.WriteLine("Answer = " + ans);

}catch (DivideByZeroException ex) {

…. ;}catch (IndexOutOfRangeException ex) {

Console.WriteLine(ex.Message); }catch (Exception ex) { }finally { }

(Source code: Module05\ExceptionHandling\ExceptionHandling\Program2.cs)

A try block can throw multiple exceptions, which can be handled by using multiple catch blocks.

We can use generalized Exception class to handle any type of runtime exception. Add the generalize catch block as the last catch block in the hierarchy otherwise at the compile time it will give an error. “A previous catch clause already catches all exceptions of this or of a super type ('System.Exception')”

Some of the Exception classes are

System.ExceptionSystem.DevideByZeroExceptionSystem.NullReferenceExceptionSyste.InvalidCastExceptionSystem.IndexOutOfRangeExceptionetc.

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finally•finally : Code in finally block is always executed. It contain clean up code to release the resources.

int num1, ans;int[ ] numarray = new int[1];try {

…; }catch (DivideByZeroException ex) {

…. ;}catch (IndexOutOfRangeException ex) {

…; }finally {

Console.WriteLine(“End of Main Block”);}

Finally can be used in such cases where it’s needed to free-up the resources always. Finally block is optional.


throw

• throw : Exceptions can be explicitly generated by using a “throw “ keyword.

int num1, num2, ans;num1 = 10, num2 = 0;

if(num1/num2){

throw new DivideByZeroException();}

We can create our own exception by creating a class and inheriting it from the Exception base class.To throw the exception throw keyword is used

throw keyword is used to raise an Exception.

Sometimes it may happen that a method that is called might be getting an exception which is handled by the caller of that method. In such situation the throw keyword is used.

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User defined Exceptions

•It is possible to create our own exception (user defined exception) classes.

•System.Exception must be base class for all the exception classes.

•In the constructor needs to define the steps which you want to perform.

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User Defined Exceptions

class BalanceException : Exception {public BalanceException(string msg)

:base(msg) { }}

class SavingsAccount {….. ;public SavingsAccount() { …. ; }public void Withdraw(float amount) {

if ((balance - amount) > 500)balance -= amount;

elsethrow new

BalanceException("Not enough balance");

}}

static void Main(){

SavingsAccount saving = new SavingsAccount();

try{

saving.Withdraw(3000);}catch (BalanceException ex){Console.WriteLine(ex.Message);

}}

User defined exception class

throw exception

(Source code: Module05\ExceptionHandling\ExceptionHandling\BalanceException.cs)

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Module 7. Other C# Features

• OverviewStructureenumType castingBoxingUnboxingref and out parameterOperator overloadingPartial classStatic class

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Structure

struct Employee {….. ;

public Employee(int id, string name, string add, float sal) {….. ;

}public float AnnualSalary() { …. ; }

}static void Main() {

Employee emp1 = new Employee(101, “Smith", "Mumbai", 2000.00f);}

•Structure is a generalization of the user defined data type. Used when a single variable is required to hold multiple types of data•Structure is a value type.

(Source code: Module06\Module06\StructureExample.cs)

Structure is a type like a class which we can define within the namespace.

The members of a structure cannot be initialized within the structure declarationA structure can have instance constructors only if they take parametersA structure can have property or methodStructure procedures cannot handle events A structure is not inheritableA structure can implement interface

Structure•Structure is Value Types. (Stack memory) •By default all elements declared in structure are public. •Can have instance constructor only if they take parameters. •Unlike classes, structure can be instantiated without using a new operator. •Structure can not inherit from other structure or classes •Structure can implement interface

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enum

•enum is a set of symbolic names that map to known numerical values.•enum is a set of named constant – collection of integer value.

enum Months{

Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec}class enumExample{

static void Main(){

Console.WriteLine(Months.Apr);Console.WriteLine((int)Months.Apr);

}}

(Source code: Module06\Module06\enumExample.cs)

By default first enumerator value start from 0 and the value of each successive enumerator is increased by 1.enum Months{

Jan=1, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec}

You can assign integer value to the individual enumerator and the value of each successive enumerator is increased by 1.enum Months{

Jan=1, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec}

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Type Casting

• Converting value type to another value typeOR

• Convert reference type to another reference type

static void Main(){

decimal number = 3.14M;int i = (int)number;Console.WriteLine("decimal value = {0}", number);Console.WriteLine("int i = {0}", i);Console.ReadLine();

}

(Source code: Module06\Module06\TypecastingExample.cs)

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Boxing - Unboxing

• Boxing is an implicit conversion of a value type to the reference type.

• Unboxing is an explicit conversion from the reference type to a value type.

static void Main() {int i = 10; //value typeobject obj = i; //boxingint j = (int)obj; //unboxingConsole.WriteLine(i.ToString());Console.WriteLine(obj.ToString());Console.WriteLine(j.ToString());Console.ReadLine();

}

Value types are stored on the stack memory and Reference types are stored on the Heap memory.

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Ref Parameter

class RefExample{

static void Methodref(ref int i){

i = 100;}static void Main(){

int number = 0;Console.WriteLine("Value of number = " + number.ToString());Methodref(ref number);Console.WriteLine("Value of number = " + number.ToString());Console.ReadLine();

}}

(Source code: Module06\Module06\RefExample.cs)

Ref parameter means argument passing by reference.

Any changes to the parameter in the method will be applied to the variable when the control passes back to the calling method.

To use the ref parameter, both the method and the calling method must explicitly use the ref keyword.

An argument passed to a ref parameter must first be initialized.

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Out Parameterclass OutExample

{static void methodout(out int i, out string str){

i = 100;str="assigned value to out parameter";

}static void Main(){

int number;string line;methodout(out number, out line);Console.WriteLine("number = " + number.ToString());Console.WriteLine("line = " + line);Console.ReadLine();

}}

(Source code: Module06\Module06\OutExample.cs)

out parameter means argument passing by reference.

Any changes to the parameter in the method will be applied to the variable when the control passes back to the calling method.

To use the out parameter, both the method and the calling method must explicitly use the out keyword.

An argument passed to an out parameter do not require to be initialized first.

Although variable passed as out arguments do not have to be initialized before being passed, the calling method is required to assign a value before the method returns.

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Operator Overloadingclass OrderItem {

private string productid;private Int32 quantity;private decimal unitprice;public string ProductID {

get { return productid; }set { productid = value; }

}public Int32 Quantity {

get { return quantity; }set { quantity = value; }

}public decimal UnitPrice {

get { return unitprice; }set { unitprice = value; }

}public decimal Total {

get { return UnitPrice * Quantity; }}

(Source code: Module06\Module06\OperatorOverloadingExample.cs)

Operator overloading means use of operator with an object.

It gives better readability

Operator overloading method always have public static access specifiers.

Operator overloading always return a type and never be void.

At least one operand must be of user defined type.

Relational operators are overloaded in pairs only.

The ref and out parameters are not allowed as arguments.

Syntax

public static return_type operator op ( argument list ){}

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Operator Overloading (Contd…)

public static OrderItem operator +(OrderItem Item1, OrderItem Item2) {if (Item1.ProductID != Item2.ProductID) {

throw new Exception("You can only add OrderItems where the ProductID is the same for both objects");

}else if (Item1.UnitPrice != Item2.UnitPrice) {

throw new Exception("You can only add OrderItems where the UnitPrice is the same for both objects");

}else {

OrderItem item = new OrderItem();item.ProductID = Item1.ProductID;item.Quantity = Item1.Quantity + Item2.Quantity;item.UnitPrice = Item1.UnitPrice;return item;

}}

}


Operators

All binary operators can be overloaded+, -, *, /, %, &, | etc.

All unary operators can be overloaded+, -, !, ~, ++, --, true, false

All relational operators can be overloaded, but only in pairs==, !=, > , <, >=, <=

Operators cannot be overloaded&&, ||, () (conversion operator), =, ., ?:, ->, new, is, as, sizeof,

Following operators are automatically overloaded when the respective binary operator is overloaded+=, -=, *=, /=

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Operator Overloading (Contd…)

static void Main() {OrderItem Item1 = new OrderItem();OrderItem Item2 = new OrderItem();OrderItem Item3;try {

Item1.ProductID = "1";Item1.Quantity = 5;Item1.UnitPrice = 10;Item2.ProductID = "1";Item2.Quantity = 4;Item2.UnitPrice = 10;

Item3 = Item1 + Item2;Console.WriteLine(Item3.Total);

}catch (Exception ex){ Console.WriteLine(ex.Message); }Console.ReadLine();

}


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Partial Typepartial class PartialTest {

public void Method2(int i) {number = i;Console.WriteLine("number = " + number);

} }partial class PartialTest {

private int number;public int Method1(int i) {

return i++;} }

class PartialExample {static void Main() {

PartialTest obj = new PartialTest();Console.WriteLine(obj.Method1(100).ToString());obj.Method2(10);Console.ReadLine();

}}

(Source code: Module06\Module06\PartialExample.cs)

Partial class means class or structure definition can be split into multiple physical files. And all files are combined when the application is compiled.

Can be used when working on a large project, allow multiple programmer to work on it simultaneously. Separate the business logic( user defined code) and system generated code in separate file. For example Windows Form

Rules of partial class•All parts require to be define in same namespace.•Each part require to be available at compile time.•Must use the same access specifiers. (public, private,…)•If any single part is defined as abstract, then the whole class is abstract.•If any single part is sealed, then the whole class is sealed.•If any part declare a base type, then the whole class inherits that base class.•Parts can specify different interface, but the whole class implements all interfaces.

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Static classstatic class Temperature {

public static double CelsiusToFahrenheit(double celsius) {

//convert celsius to fahrenheitdouble Fahrenheit = (celsius * 9 / 5) + 32;return Fahrenheit;

}public static double

FahrenheitToCelsius(double fahrenheit) {double Celsius = (fahrenheit - 32) * 5 / 9;return Celsius;

}}

class StaticExample {static void Main(){

double F, C;F= 100;C = 35;Console.WriteLine("{0} degree Celsius

temperature in Fahrenheit: {1:F2}",C, Temperature.CelsiusToFahrenheit(C));

Console.WriteLine("{0} degree Fahrenhit temperature in Celsius: {1:F2}",F, Temperature.FahrenheitToCelsius(F));

Console.ReadLine(); }}

(Source code: Module06\Module06\StaticExample.cs)

Static class means class cannot be instantiated. It can contain only static members. And the class is sealed means cannot be inherited.

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Auto - Implemented Property

class Person {public string Name{

get;set;

}public int Age{

get;set;

}}

(Source code: Module06\Module06\ObjectInitializerExample.cs)

Auto implemented PropertyAuto-implemented properties make property-declaration more concise when no additional logic is required in the property accessor.

Automatic properties allow you to avoid declaring manually a private field and write the get/set accessor -- instead the compiler create the private field and the default get/set accessor.

You cannot write any validation for auto implemented properties.

Auto-implemented properties must declare both a get and a set accessor.

To create a readonly auto-implemented property, give it a private set accessor.

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Object Initializer

class ObjectInitializerExample{

static void Main(){

Person pobj = new Person { Name = "Bhavana", Age = 18 };Console.WriteLine("Name = " + pobj.Name);Console.WriteLine("Age = " + pobj.Age);Console.ReadLine();

}}

(Source code: Module06\Module06\ObjectInitializerExample.cs)

Object initializer allow you to include an initializer that specifies the initial values of the members of a newly created object.

This enables you to combine declaration and initialization in one step.

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Module 8. String, StringBuilder, Dateformat

• OverviewUseful method of string class.StringBuilder class.Dateformats.Output formats.

100


String Class methods

• Various property and methods of string class• Property of string class• Length

Gets the number of characters.

string s= "welcome";Console.WriteLine(s.Length); //7

(Source code: Module07\StringExample\StringExample\Program.cs)

String is an immutable, means data cannot be changed. Whenever we try to change the data of string type, it is returning or creating brand new string object

Escape Characters\’ – Single quote\” – double quote\\ - file paths\a – triggers system alert(beep)\n – new line\t – horizontal tab

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String class methods (Contd…)

• Comparing StringsThe compare method compares two strings and returns an integer value

string s = "welcome";string s1 = "Welcome";int i;i = string.Compare(s, s1);Console.WriteLine(i); //-1s = "welcome";s1 = "welcome";i = string.Compare(s, s1);Console.WriteLine(i); //0s = "Welcome";s1 = "welcome";i = string.Compare(s, s1);Console.WriteLine(i); //+1


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• Concatthe concat method concatenate two strings and returns a new stringstring s = "Hello";string s1 = "World";Console.WriteLine(string.Concat(s, s1)); //HelloWorid

• CopyCreates a new instance of string with the same value as a specified stringstring s = "Hello";string s1;s1 = string.Copy(s);Console.WriteLine(s1);


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• Ends withDetermines whether the end of the string matches the specified string. Returns boolean result true or false.string s = "Welcome";

Console.WriteLine (s.EndsWith ("me")); // true

• EqualsDetermines whether two String objects have the same value. Returns Boolean result true or false.string s = "Welcome";string s1= "welcome";Console.WriteLine(s.Equals(s1)); //false


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• IndexOfReturn the index of the given String parameter in a Searched String.string s= "Welcome";int i = s.IndexOf ("e"); //1Console.WriteLine(i);i = s.IndexOf ("e", 2); //6Console.WriteLine(i);

• LastIndexOfReturns the index position of the last occurrence of a specified String within the Searched String.string s= "Welcome";int i = s.LastIndexOf ("e"); //6Console.WriteLine(i);


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• PadLeftRight-aligns the String, padding on the left with spaces or a specified character for a specified total length.

• PadRightLeft-aligns the String, padding on the right with spaces or a specified character, for a specified total length.

string s= "Welcome";Console.WriteLine(s.PadLeft(10, '*')); //***WelcomeConsole.WriteLine(s.PadRight(10, '*')); //Welcome***


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• RemoveRemove the characters from specified position in a given String.string s= "Welcome";Console.WriteLine(s.Remove(3, 4)) ; // Wel

• ReplaceReplaces all occurrences of a specified character or String, with another specified character or string.string s = "Welcome";

Console.WriteLine (s.Replace ("e", "a")); // Walcoma


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• StartWithDetermines whether the beginning of the String matches the specified String parameter. Returns Boolean value true or false.string s = "Welcome";Console.WriteLine (s.StartsWith ("We")); // true

• SubstringReturns part of a string string s = "Welcome";Console.WriteLine(s.Substring(3)); // comeConsole.WriteLine(s.Substring(3, 3)); // com


108



• ToLowerReturns a String in lowercase

• ToUpperReturns a copy of the String in uppercase.string s= "WELCOME";Console.WriteLine (s.ToLower()); // welcomestring s1 = "welcome";Console.WriteLine (s1.ToUpper()); //WELCOME

• ToStringConverts the value to a String type.


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• TrimRemoves all occurrences of a set of specified character from thebeginning and end of the String.

• TrimEndRemoves all occurrences of a set of specified character from the end of the String.

• TrimStartRemoves all occurrences of a set of specified character from thebeginning of the String.

String s= "-----------WELCOME-----------";Console.WriteLine (s);Console.WriteLine (s.Trim('-')); //WELCOMEConsole.WriteLine (s.TrimEnd('-')); //-----------WELCOMEConsole.WriteLine (s.TrimStart('-')); //WELCOME----------


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StringBuilder Class• The StringBuilder class represents a mutable string of characters.


StringBuilder builder = new StringBuilder("Hello wrold. ");Console.WriteLine(builder);builder.Append("This is class test.");Console.WriteLine(builder);builder.Insert(21, "StringBuilder ");Console.WriteLine(builder);builder.Remove(5, 6);Console.WriteLine(builder);builder.Replace(".", "!");Console.WriteLine(builder);Console.WriteLine("Length = " + builder.Length);Console.ReadLine();

}

(Source code: Module07\StringBuilderExample\StringBuilderExample\Program.cs)

A string is a sequential collection of Unicode characters used to represent text. It is immutable because once specified the text can not be changed. There are methods to modify string but they will return a new string object with the changes made. These changes will not happen to the existing string object.

The StringBuilder class represents a mutable string of characters. It's called mutable because it can be modified once it has been created by using Append, Insert, Remove, and Replace methods. The changes will happen to the existing StringBuilder object

The StringBuilder class is defined in the System.Text namespace.


Date formats

Specifier Description Output

d Short Date 8/4/2012

D Long Date 8-Apr-12

t Short Time 21:08

T Long Time 21:08:59

f Full date and time 4/8/2012 21:08

F Full date and time (long) 4/8/2012 21:08

g Default date and time 8/4/2012 21:08

G Default date and time (long) 8/4/2012 21:08


Date formats continued…


M Day / Month 8-Apr

r RFC1123 date Sun, 08 Apr 2012 21:08:59 GMT

s Sortable date/time 2012-04-08T21:08:59

u Universal time, local timezone 2012-04-08 21:08:59Z

Y Month / Year Apr-12

dd Day 8

ddd Short Day Name Sun

dddd Full Day Name Sunday




hh 2 digit hour 9

HH 2 digit hour (24 hour) 21

mm 2 digit minute 8

MM Month 4

MMM Short Month name Apr

MMMM Month name April

ss seconds 59

tt AM/PM PM




yy 2 digit year 7

yyyy 4 digit year 2012

: seperator, e.g. {0:hh:mm:ss} 9:08:59

/ seperator, e.g. {0:dd/MM/yyyy} 8/4/2012



DateTime time = DateTime.Now;string format = "ddd"+" "+"dd-MMM-yyyy";Console.WriteLine(time.ToString(format));Console.ReadLine();


Output formats

Character Description Examples OutputC or c Currency Console.Write("{0:C}", 2.5); $2.50

Console.Write("{0:C}", -2.5); ($2.50)D or d Decimal Console.Write("{0:D5}", 25); 25E or e Scientific Console.Write("{0:E}", 250000); 2.50E+05F or f Fixed-point Console.Write("{0:F2}", 25); 25

Console.Write("{0:F0}", 25); 25

G or g General Console.Write("{0:G}", 2.5); 2.5N or n Number Console.Write("{0:N}", 2500000); 2,500,000.00

X or x Hexadecimal Console.Write("{0:X}", 250); FA

Console.Write("{0:X}", 0xffff); FFFF

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117


Module 9. Collections

• OverviewSystem.Collections Namespace.ArrayListHashTableCollection Initializer

118


Collection Classes

• A collection is a set of objects.• Using collection we can organize and manipulate the objects.• Can keep the track of objects.• The System.Collection namespace contains the different

types of collection classes, such as Stack, Queue, ArrayList, HashTable, etc.


ArrayList

• ArrayList is a collection of element of different types.• It increases the size of the storage location as required.• It stores the value as object.• It represents dynamically sized array of objects.• It is contained in the namespace System.Collections;

120


ArrayList ExampleUsing System.Collection;static void Main(string[ ] args) {

ArrayList countryList = new ArrayList();countryList.Add("India");Console.WriteLine("Total items = " +

countryList.Count.ToString());for (int i = 0; i < countryList.Count; i++) {

Console.WriteLine(countryList[i].ToString()); }//insert value

countryList.Insert(1, "France");Console.WriteLine("\n-------print specific

item form the arraylist object-------\n"); Console.WriteLine(countryList[2].ToString());

}

//reversecountryList.Reverse();//sort countryList.Sort();

//RemoveAt()countryList.RemoveAt(2);//Clear()countryList.Clear();

}

(Source code: Module07\CollectionExample\CollectionExample\ArrayListExample.cs)ArrayList is the collection of elements of different typeElements in this collection can be accessed using an integer index. Indexes in this collection are zero-based.


HashTable

• HashTable object contains Items in key and value pair.• Keys are used as indexes. • Values can be searched by using keys.

MH

GA

GJ

TN

AP

RJ

Maharashtra

Goa

Gujrat

Tamilnadu

Andra pradesh

Rajasthan

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HashTable Examplestatic void Main() {

Hashtable hashlist = new Hashtable();

hashlist.Add("txt", "notepad.exe");

hashlist.Add("bmp", "paint.exe");hashlist.Add("rtf",

"wrodpad.exe");// The Add method throws an

exception if the new key is already in the hash table.

try {hashlist.Add("txt",

"winword.exe");}catch {

Console.WriteLine("An element with Key txt already exists.");

}

Console.WriteLine("\n-------------------------------\n");

//DictionaryEntry - Defines a dictionary key/value pair that can be set or retrieved.

foreach (DictionaryEntry de in hashlist) {

Console.WriteLine("Key = {0}, Value = {1}", de.Key, de.Value);

}Console.WriteLine("\n------------------------

-------\n");//Printing the value of the specific keyConsole.WriteLine("For key = rtf, value

= {0}.", hashlist["rtf"]);Console.ReadLine();

}

(Source code: Module07\CollectionExample\CollectionExample\HashTableExample.cs)

HashTable represents a collection of key/value pairs that are organized based on the hash code of the key.


Stack

• Stack represents last-in-first-out (LIFO) .• You may assume kitchen dish stack. You can pull out a top

most dish which is kept in stack very last.• It simply consists of non-generic collection of objects.

pop push

012345

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Stack Example

static void Main() {Stack stackobj = new Stack();stackobj.Push("Hello");stackobj.Push("Stack");stackobj.Push("class");stackobj.Push("example");Console.WriteLine("Count = " +

stackobj.Count.ToString());Console.WriteLine("\n-------------------

\n");foreach (Object obj in stackobj){

Console.WriteLine(obj.ToString());}

Console.WriteLine("\n---------Top Element- peek method---------\n");

Console.WriteLine(stackobj.Peek());Console.WriteLine("\n---------Top

Element- pop method---------\n");Console.WriteLine(stackobj.Pop());Console.WriteLine("\n---------count---

-------\n");Console.WriteLine("Count = " +

stackobj.Count.ToString());foreach (Object obj in stackobj){

Console.WriteLine(obj.ToString());}Console.ReadLine();

}


Queue

• Queue represents first-in-first-out (FIFO) .• We can Enqueue (add) items in queue.• We can Dequeue (remove) items from queue.

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Queue Classstatic void Main() {

Queue queueobj = new Queue();queueobj.Enqueue("Hello");queueobj.Enqueue("Queue");queueobj.Enqueue("class");queueobj.Enqueue("example");Console.WriteLine("Count = " + queueobj.Count.ToString());foreach (Object obj in queueobj) {

Console.WriteLine(obj.ToString());}Console.WriteLine("\n---------Top Element- ---------\n“, queueobj.Dequeue());Console.WriteLine("\n---------count----------\n“, queueobj.Count.ToString());foreach (Object obj in queueobj) {

Console.WriteLine(obj.ToString());}Console.ReadLine();

}

(Source code: Module07\CollectionExample\CollectionExample\QueueExample.cs)


Linked List

• A Linked list is a data structure consisting of group nodes which together represents a sequence.

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Collection Initializer

• Able to give values to collections in a concise and compact manner

static void Main(){

ArrayList countryList = new ArrayList { "India", "Usa", "Japan" };for (int i = 0; i < countryList.Count; i++){

Console.WriteLine(countryList[i].ToString());}Console.ReadLine();

}

(Source code: Module07\CollectionExample\CollectionExample\CollectionInitializerExample.cs)

129


Module 10. Generics and Nullable Types

• OverviewLimitations of Collection ClassesUnderstanding GenericsAdvantages of generics over collectionNullable Types

130


Limitation of Collection Classesclass Person {

string name, address;public Person(string name, string address) {

this.name = name; this.address = address; }

public void Display(){Console.WriteLine ("Name = " + name);Console.WriteLine("Address = " + address);

} }static void Main(string[] args) {

ArrayList list = new ArrayList();list.Add(new Person("Bhavana", "Mumbai"));list.Add(new Person("Vishal", "Mumbai"));list.Add("Krishna");

for (int i = 0; i < list.Count; i++) {list[i]. //error 1

//error 2((Person)list[i]).Display();

}

//error 3int temp =int.Parse( list[0].ToString()); }

Whenever we store any data to the collection class object they are always maintained as Object type. Because of this it is possible that we can store different type of data in collection object.This feature one way is advantageous that we can store different types of value in collection, but this feature also have some disadvantages

Error 1We are storing different type of values in the ArrayList object We have added the object of Person class which is user defined type.While retrieving the members of the list object we typed list[i]. Which gives public member of the Object class only and it will not give the public member which you have defined in Person class.

Error 2You require to explicitly typecast the member. After typecasting it will give the public member of the Person class. But it will give an error at the run time when in the for loop when we try to retrieve the third item which is not of the Person type.

Error 3At the compilation time it allows us to convent any member of the ArrayList to int type or any other type. But at the run time when it require to assign the value of user defined type to an int type it will give an error.


Why Generics?

• In the earlier code example two major issues were faced as follows:

Boxing and unboxing overhead : Boxing and unboxing operations lead to performance overhead since it involves dynamic memory allocation and runtime type check.No strong type data at compilation time : The earlier code is technically correct. Error will be not be thrown at compile time. But when the code is executed it will throw an exception InvalidCastException.

• Generics has solution for these limitations.


Generics

• Type Safety -- Generic types enforce type compliance at compile-time, and not run-time (as in the case of using Object). This reduces the chances of data-type conflict during run-time

• Performance -- The data types to be used in a Generic class are determined at compile-time, hence there is no need to perform type casting during run-time, which is a computationally costly process.

• Code reuse -- Since you only need to write the class once and customize it to use with the various data types, there is a substantial amount of code-reuse.

Comparison between Generic, Collection and Array

•To define an array, we have to give the fix size. The size can’t be dynamically increased. Every time reallocation of memory happens.•Collections are dynamic. To store or retrieve a value, it performs boxing and un-boxing which affects performance considerably.•Whereas generics are type safe. While defining it we have to provide a type. No other type value can be stored.

132

133


Generics List<T> Collectionstatic void Main() {

List<string> liststr = new List<string>();liststr.Add("Vishal");liststr.Add("Amit");//liststr.Add(new Person("Pankaj", "Mumbai")); //compile time error

for (int i = 0; i < liststr.Count; i++) {Console.WriteLine(liststr[i]);

}Console.WriteLine("\n-------------------------------\n");List<Person> listperson = new List<Person>();listperson.Add(new Person("Bhavana", "Mumbai"));listperson.Add(new Person("Pankaj", "Mumbai"));for (int i = 0; i < listperson.Count; i++) {

listperson[i].Display();}Console.ReadLine();

}


Generic Dictionary<key,value> collectionclass Customers {

….public Customers(string Name, string Location) {

….. }public int CustId { get ; }public string CustName { get; set; }public string CustLocation {get; set; }public void displayCust() { … }

}static void Main(string[] args) {

Dictionary<int, Customers> customerDictionary = new Dictionary<int,Customers>();Customers customer3 = new Customers("Anju", "Borivali");Customers customer4 = new Customers(“Amit", "Kalyan");foreach (KeyValuePair<int, Customers> custKeyValue in customerDictionary)

{Console.WriteLine( custKeyValue.Key, custKeyValue.Value.CustName,

custKeyValue.Value.CustLocation);}

Generic Dictionary collection stores information into key/value pair. There is a non generic collection HashTable which also stores the information into key/value pair. But it stores data of type object.

134

135


Creating our own Generic Classesclass GenericClass<T> {

T value1, value2;public UserdefinedGeneric(T val1, T val2) {

value1 = val1;value2 = val2;

}public void Swap() {

T temp = value1;value1 = value2;value2 = temp;Console.WriteLine(value1 + " “ + value2);

}}

static void Main(string[] args) {UserdefinedGeneric<string> obj1 = new UserdefinedGeneric<string>("Trupti", “Hello");

obj1.Swap();UserdefinedGeneric<int> obj2 = new UserdefinedGeneric<int>(“25", “50");

obj2.Swap();

Generic is a technique with which you can delay the specification of the type of one or more programming elements in a class or a method ,until the time of the usage of that class or method.With generics instead of specifying the data type of the parameters, you define labels, which can later be replaced by the data type that the user specifies at the time of using the generic method or class

Generic is a type parameter, which allows to design a class or method where the value of the type is specified at the time of instantiating class or usage of a method.

136


Nullable Typestatic void Main() {

int number1 = 10; Nullable<int> number2 = null; int? number3 = null;try {

Console.WriteLine("number1 = " + number1.ToString());Console.WriteLine("number2 = " + number2.Value);Console.WriteLine("number3 = " + number3.ToString());Console.WriteLine("\n------------------------------\n");if (number2.HasValue == true)

Console.WriteLine("number2 = " + number2.Value);else

Console.WriteLine("Null value");Console.WriteLine("\n------arithmatic operation with nullable type--------\n");Console.WriteLine(number1 + number2.GetValueOrDefault(0));number2 = 100;Console.WriteLine(number1 + number2.GetValueOrDefault(0));

}catch (Exception ex) { Console.WriteLine(ex.Message); }Console.ReadLine();

Nullable type

One of the primary differences between value types such as int or structures and reference types such as string is that reference types support a null value. That is to say, a reference type variable can contain the value null, which means that the variable doesn't actually refer to a value. In contrast, a value type variable always contains a value. An int variable always contains a value, even if that number is zero.

Nullable type adds nullability to any value type.

137


Module 11. Windows Form - I

• OverviewIntroduction to Window Forms IDECreating forms with controlsResponding to form eventsUsing basic controls (e.g. Label, TextBox, Button, etc.)Anchor and Dock Properties

138


Visual Studio IDE

ToolBox Form Design View Solution Explorer Property Window

GUI application helps us to create user interface. A well designed interface makes the application more users friendly. In a windows based application, user interface is accomplished with windows Forms and controls. Windows form is a base container for user interface. A control is an object that can be drawn on to the Form to enable or enhance user interaction with the application. Examples of these control, TextBox, Button, Label, Radio Button etc. All these Windows Controls are based on the Control class, which is the base class for all controls.

To create GUI application, Start Visual Studio .Net, from Project Window select Template type as Windows Application. System will open visual studio .net IDE which include Form Designer, Solution Explorer, Property window, toolbox etc.

139


Introduction to Controls

Label TextBox MultiLineTextBox

ListBox CheckBox

RadioButton Button GroupBoxComboBox

Form is a base unit on which we can place the controls. Every controls including Form will have properties, methods and events.

Forms propertiesText – Value to be display in the title barWindowState – Initial visual state of a form

140


Label Example• Display dynamic time.

private void timer1_Tick(object sender, EventArgs e){

lbldatetime.Text = DateTime.Now.ToString();}

private void DynamicTime_Load(object sender, EventArgs e){

lbldatetime.Text = DateTime.Now.ToString();

}

(Source code: Module10\WinForm1\WinForm1\DynamicTime.cs)

LabelProperties

Name – lbldatetimeText – empty

Timer control from the component tabProperties

Enable – TrueInterval – 1000

141


MessageBox Class

• Use to display informative message to the user and can take user confirmation.

• MessageBox.Show("Welcome to GUI Application");

(Source code: Module10\WinForm1\WinForm1\Form1.cs)

Static method MessageBox.show() is used to accept the message, title, buttons and icon as parameters. Only message is the compulsory parameter.

142


Login Form Example

public partial class LoginForm : Form {int count = 0;public LoginForm() {

InitializeComponent();}

private void btncancel_Click(object sender, EventArgs e) {this.Close();

}

(Source code: Module10\WinForm1\WinForm1\LoginForm.cs)

Design a form which accept user name and password. Check username as “pragati” and password as “admin”. If username and password are correct then show the Win Form welcome else display the proper error message in the message box. Give three chance to write the correct username and password else display appropriate message and close the application.

LabelDisplay static text from providing information.

PropertiesName - Control NameText – Value to be displayedAutoSize – Allow automatic resizing according to the txt length

143


Login Form Example (Contd…)

private void btnsubmit_Click(object sender, EventArgs e) {if (txtusername.Text == "pragati" && txtpwd.Text == "admin") {

Welcome frm = new Welcome();this.Hide();frm.Show();

}else {

MessageBox.Show("Invalid username or password. Please provide the correct value", "Login");

count = count + 1;txtusername.Clear();txtpwd.Clear();txtusername.Focus();

}if (count == 3) {

MessageBox.Show("Sorry! Please try again", "Login");this.Close();

}}

(Source code: Module10\WinForm1\WinForm1\LoginForm.cs)

TextBoxDisplay text to the user and accept the input from the user.

PropertiesName – Control NameText – Display or accept the textMultiline – convert single line textbox into multi line textboxPasswordChar – set a character that acts as a placeholder for the characters.

ButtonPerform an action

PropertiesName - Control nameText – Value to be displayedAutoSize – Controls automatically size itself to fit its content.Image – Image to be displayed

144


Welcome Form

private void btnclose_Click(object sender, EventArgs e){

Application.Exit();}

(Source code: Module10\WinForm1\WinForm1\Welcome.cs)

This.Close() will close the individual form while Application.Exit() method will close all the form which are loaded in memory for that application.

145


ComboBox Example

(Source code: Module10\WinForm1\WinForm1\ComboBoxExample.cs)

Select your qualification and computer skills from the list given below.

Select the country from the combo dropdown. If users want he/she can add the country name in the combo dropdown. While adding the new data keep check that no duplication allowed. Same time if user wants he/she can delete the country name from the list.

ComboBoxDisplay a drop down list of items, from which user can select any one item.

PropertiesName – Control nameText – Selected text from the listItems – Collection of the items to be displayed in drop downDropdownStyle – Appearance and functionality of combo box

Add some country name in combo box at design time by using Items property. We can also add data dynamically.

146


ComboBox Example (Contd…)

private void btnadd_Click(object sender, EventArgs e) {int i, flag =0;for( i=0;i<cmbcountry.Items.Count;i++) {

if (cmbcountry.Items[i].ToString() == (txtcountry.Text).ToUpper()) {flag=0;break;

}else

flag=1;}if (flag==1) {

cmbcountry.Items.Add(txtcountry.Text.ToUpper());txtcountry.Clear();MessageBox.Show("Country added");

}else {

txtcountry.Clear();MessageBox.Show("Country present cannot add duplicate");

}}


147


ComboBox Example (Contd…)

private void btnremove_Click(object sender, EventArgs e){

txtcountry.Text = "";cmbcountry.Items.RemoveAt(cmbcountry.SelectedIndex);

}

private void cmbcountry_SelectedIndexChanged(object sender, EventArgs e){

int itemno = cmbcountry.SelectedIndex;

txtcountry.Text = cmbcountry.Items[itemno].ToString();}


148


ListBox Example

(Source code: Module10\WinForm1\WinForm1\ListBoxExample.cs)

ListBoxDisplay a list of items, from which user can select one or more items

PropertiesName – Control nameItems – Collection of the items to be displayed in list boxSelectionMode – Method in which items are selected. One, MultiSingle,

MultiExtended.

Difference between Combo box and List box Listbox support multiple selection from the given options, while ListBox allows

only single selection.

149


ListBox Example (Contd…)

private void btnlist_Click(object sender, EventArgs e){

int i;string str = "Qualification";for (i = 0; i <= lstqualification.Items.Count - 1; i++){

if (lstqualification.GetSelected(i) == true){

str += "\n";str += lstqualification.Items[i];

}}Label3.Text = str;

}


150



private void btnmultiselect_Click(object sender, EventArgs e){

ListBox.SelectedIndexCollection listboxcollection = lstqualification.SelectedIndices;MessageBox.Show(listboxcollection.Count.ToString());string str = null;for (int i = 0; i < listboxcollection.Count; i++){

int index = listboxcollection[i];str += lstqualification.Items[index].ToString()+ " ";

}MessageBox.Show (str);

}


151



private void btnchecklist_Click(object sender, EventArgs e){

string str = "Computer Skill";for (int i = 0; i <= clstskill.Items.Count - 1; i++){

if (clstskill.GetItemChecked(i) == true){

str += "\n";str += clstskill.Items[i];

}}Label4.Text = str;

}


152


RadioButton Example

(Source code: Module10\WinForm1\WinForm1\RadioButtonExample.cs)

Create an application which accept the amount and convert into rupee. The amount can be converted from dollar or pound to rupee.

For creating a group of Radio Buttons we require to use either GroupBox or Panel, which will work as a base container for the RadioButtons.

GroupBoxThe GroupBox displays a frame around a group of controls with or without a

caption. Use a GroupBox to logically group a collection of controls on a form. The GroupBox is a container control.

PropertiesName – Control NameText – Get or Set the Caption Value.

153


RadioButton Example (Contd…)

private void rbdollar_CheckedChanged(object sender, EventArgs e) {if (rbdollar.Checked==true) {

decimal amount= decimal.Parse(txtamount.Text)*45;lblresult.Text = "Converted amount = " + amount.ToString();

}else

lblresult.Text="";}private void rbpound_CheckedChanged(object sender, EventArgs e) {

if (rbpound.Checked==true) {decimal amount= decimal.Parse(txtamount.Text)*70;lblresult.Text = "Converted amount = " + amount.ToString();

}else

lblresult.Text="";}

(Source code: Module10\WinForm1\WinForm1\RadioButtonExample.cs)

Panelcontains other controls.PropertiesName Control NameAutoScroll – Gets or sets a value indicating whether the container will allow the user to scroll to any controls placed outside of its visible boundaries.Border Style - Indicates the border style for the control

RadioButtonFrom a given choice user can select any one option.

Name – Control NameText – Get or Set the text associated with the control.Checked – Gets or Sets a value indicating whether the control is checked.

154


CheckBox Example

(Source code: Module10\WinForm1\WinForm1\CheckBoxExample.cs)

CheckBoxFrom a given choice user can select one, multiple, all or none.

PropertiesName – Control NameText – Get or set the text associated with the controlChecked – Indicates whether the check box is checked or unchecked

155


CheckBox Example (Contd…)

private void CheckSkill() {string skills = "Skills = ";for (int i=0;i<Controls.Count ;i++) {

string cnt = Controls[i].GetType().ToString();if (cnt == "System.Windows.Forms.CheckBox") {

CheckBox cb= (CheckBox) Controls[i];if (cb.Checked==true)

skills += " " + cb.Text;}

}txtresult.Text=skills;

}private void chkoffice_CheckedChanged(object sender, EventArgs e) {

CheckSkill(); }private void chkprg_CheckedChanged(object sender, EventArgs e) {

CheckSkill(); }private void chkdb_CheckedChanged(object sender, EventArgs e) {

CheckSkill(); }private void chkweb_CheckedChanged(object sender, EventArgs e) {

CheckSkill(); }

(Source code: Module10\WinForm1\WinForm1\CheckBoxExample.cs)

156


MessageBox Exampleprivate void btnStart_Click(object sender,

EventArgs e) {DialogResult result =

MessageBox.Show ("Do you want to start an Excel Application?“ , "MessageBox Example", MessageBoxButtons.YesNo,

MessageBoxIcon.Question);if (result == DialogResult.Yes )

System.Diagnostics.Process.Start("excel.exe");else

this.Close();}

When user click the Ms excel Button take the conformation from the user, if user click yes button start excel application else close the current application.MessageBox.Show ( “Message”, “Title”, MessageBoxButtons, MessageBoxIcon);MessageBoxButtons Enumeration

Combination of buttons

OKOKCancelAbortRetryIgnoreYesNoCancelYesNoRetryCancel

Integer values of the individual memberOk 1Cancel 2Abort 3Retry 4Ignore 5Yes 6No 7

MessageBoxIcon enumerationQuestionStopExclamationWarning

157


Anchor Property

• When a control is anchored to an edge of its container the distance between the control and specified edge remains constant when container resizes.

A control can be anchored to one or more edges of its parent container. Anchoring a control to its parent ensures that the anchored edges remain in the same position relative to the edges of the parent container when the parent container is resized.

158


Dock Property

• Align control to the edges of the form by setting the Dock property.

Top

Bottom

FillLeft Right

Control Location of the dock property

Setting Effects

DockStyle.Top Dock to the top of the form

DockStyle.Bottom Dock to the bottom of the form

DockStyle.Left Dock to the left of the form

DockStyle.Right Dock to the right of the form

DockStyle.Fill Fill remaining space in the form

DockStyle.None Does not dock anywhere

159


Module 12. File I/O

• OverviewSystem.IO NamespaceThe Directory and File ClassesThe FileStream ClassReading and Writing to File using StreamReader and StreamWriter.

160


Input and Output

• Input means reading• Output means writing

Standard input – keyboard and mouseStandard output – Monitor and printer

• Import System.IO namespace


File IO

File

File Stream

Stream Reader/ Stream Writer

Binary Reader/ Binary Writer

Stream

File is a persistent storage where data is stored in bytes, known as a stream and we can perform input / output operations i.e. we can read and write to a file. In C# to use file handling we required to use System.IO namespace with a class library that supports string, character and file manipulation. These classes contain properties, methods and events for creating, copying, moving, and deleting files and directories.The parent class of file processing is Stream. With Stream, you can store data to a stream or you can retrieve data from a stream. Stream is an abstract class, which means that you cannot use it to declare an object in your application. The most commonly used classes are FileStream, StreamReader and StreamWriter.

The Directory class in C# allows us to create and work with Folders/Directories. With this class you can create, edit and delete folders and also maintain drives on the machine.

161


File IO classes

Stream

Stream Reader

Text Reader Text Writer

Stream Writer

File Stream

Binary Reader

Binary Writer

Network Stream

Base class in File IO operations is Stream class which is present in System.IOnamespace. File IO provides various stream classes such as StreamWriter, StreamWriter, File Stream, BinaryReader, BinaryWriter, NetworkStream etc…

162

The Directory class in C# allows us to create and work with Folders/Directories. With this class you can create, edit and delete folders and also maintain drives on the machine.


The Directory Class

•Method of the Directory class

Remove the directory and its contents.Directory.Delete(“c:\\examples”)

Delete

Checked whether the directory exist at the specified location if exists return true else false.Messagebox.show(Directory.Exists(“c:\\examples”))

Exists

Create a directory at a specified path locationDirectory.CreateDirectory(“c:\\examples”)

CreateDirecotryUseMethod


The Directory Class (Contd…)

Returns the names of all sub directory available under specified pathAdd textbox and buttonOn click event of the button write the following code.Int I;String[ ] dir;dir = Directory.GetDirectories("c:\\")For (i=0;i<dir.Length;i++) {

TextBox1.AppendText(dir[i] + “\n”);}

GetDirectories



Returns the names of all files available under specified pathint i;String[ ] file; file = Directory.GetFiles("c:\\")For (i=0;i<file.Length;i++) {

TextBox1.AppendText(file[i] + “\n”);}

GetFiles

Returns the parent directory of the specified pathDirectoryInfo di;di = Directory.GetParent("c:\\examples")MessageBox.Show(di.ToString())

GetParent

Return the root information about the specified pathDirectory. GetDirectoryRoot(Messagebox.show(“c:\\examples”) )

GetDirectoryRoot



Retruns the name of the logical drives of the computerInt I;String[ ] drive;drive = Directory.GetLogicalDrives();for (i=0;i<drive.length;i++) {

TextBox1.AppendText(drive[i] + “\n”);}

getLogicalDrives

Move a file or a directory to a new locationDirectory.move(“c:\\sample\data”, c:\\examples\data”)

Move

167


FileStream Class

• This class provides access to standard input and output files.

• FileStream fs = new FileStream(“path”, FileMode);

This class provides access to standard input and output files. We use the members of FileModeenumerations with the constructors of this class to create or open a file. After a file is opened it's FileStream object can be passed to the StreamReader and StreamWriter classes to work with the data in the file.

File ModesAppend - Open the file if it exists and seek to the end of the file, or create a new

file.Create - Create a new file. If file exists, it will be overwritten.CreateNew - Create a new file. If file exists, throw an exception.Open - Open an existing file.OpenOrCreate - Open a file if it exists, otherwise create a new fileTruncate - Open an existing file, once opened the file should be truncated so that its

size is zero. If file does not exist, throw an exception.


StreamReader and StreamWriter Class

168


Save Button Codeusing System.IO;savefiledialog = new SaveFileDialog();savefiledialog.CheckPathExists = true;savefiledialog.Filter = "Text Files (*.txt)|*.txt|All Files (*.*)|*.*";savefiledialog.Title = "Save File as ";savefiledialog.FilterIndex = 2;savefiledialog.InitialDirectory = @"C:\";savefiledialog.RestoreDirectory = true;if (savefiledialog.ShowDialog() == DialogResult.OK){

FileStream file = new FileStream(savefiledialog.FileName, FileMode.Create);StreamWriter writer = new StreamWriter(file);writer.WriteLine(rtbData.Text);MessageBox.Show("File created successfully");writer.Close();

}

169


Open Button Code

• Open button Click Event

OpenFileDialog openfiledialog = new OpenFileDialog();openfiledialog.Title = "Open file..";openfiledialog.InitialDirectory = @"C:\";openfiledialog.RestoreDirectory = true;if (openfiledialog.ShowDialog() == DialogResult.OK) {

FileStream file = new FileStream(openfiledialog.FileName, FileMode.Open);StreamReader reader = new StreamReader(file);rtbData.AppendText(reader.ReadToEnd());reader.Close();

}

170


Write and Read using same stream

• Write&Read button click eventFileStream stream = new FileStream("c:\\data.txt", FileMode.OpenOrCreate );StreamWriter writer = new StreamWriter(stream);StreamReader reader = new StreamReader(stream);writer.WriteLine("Testing writing and reading from the same file");writer.WriteLine("This concept is interesting \n");writer.Flush();reader.BaseStream.Seek(0, SeekOrigin.Begin);WorkArea.Text = reader.ReadToEnd();writer.Close();reader.Close();stream.Close();

171


Binary Reading and Writing

Binary is basically used to read primitive data.

172


BinaryWriter and BinaryReader Code

FileStream stream = new FileStream("c:\\binary.txt", FileMode.Create);

BinaryWriter writer = new BinaryWriter(stream);

writer.Write(WorkArea.Text);WorkArea.Clear();writer.Close();stream.Close();

FileStream stream = new FileStream("c:\\binary.txt", FileMode.Open );BinaryReader reader = new BinaryReader(stream);while (reader.PeekChar() != -1) {

char c = reader.ReadChar();WorkArea.AppendText(c.ToString());if (c == ' ‘) {

WorkArea.AppendText("\n");}}

reader.Close();stream.Close();

173


Split method

• Use as a string tokenize

string str = textBox1.Text;int count =str.Split(new char[] {' '}).Length ;MessageBox.Show(count.ToString());

175


Input Form

Create the registration form which takes the input from the user. When user click on “Save” button it will store the information to the file..When user click on “Clear” button it will clear information form the input controls.When user click on “Display existing users” checkbox, it will display all the files available in c:\Users folder in ListBox. By selecting any of the file you can view the information in the Rich Text Box.

176


Input Form Codeprivate void Registration_Load(object sender, EventArgs e){

List<string> country = new List<string> {"India","Usa","Japan","Uk","France"};cmbcountry.DataSource = country;List<string> qualification = new List<string> { "Graduate", "Post graduate", "CA",

"MBA", "Doctor", "Engineer", "MCA" };lstqualification.DataSource = qualification;

}private void chktel_CheckedChanged(object sender, EventArgs e) {

if (chktel.Checked == true)txttel.Enabled = true;

elsetxttel.Enabled = false;

}private void chkmobile_CheckedChanged(object sender, EventArgs e) {

if (chkmobile.Checked == true)txtmobile.Enabled = true;

elsetxtmobile.Enabled = false;

}

177


Input Form Code (Contd…)

private void btnsave_Click(object sender, EventArgs e) {

string tel = null, mobile = null, gender = null, status = null, qualification = null, message = null;

string name = txtuname.Text;string pwd = txtpwd.Text;string address = txtaddress.Text;int itemno = cmbcountry.SelectedIndex;string country =

cmbcountry.Items[itemno].ToString();if (txttel.Text != "")

tel = txttel.Text;else

tel = "No Telephone";if (txtmobile.Text != "")

mobile = txtmobile.Text;else

mobile = "No Mobile";

if (rdbmale.Checked == true)gender = "Male";

if (rdbfemale.Checked == true)gender = "Female";

if (rdbsingle.Checked == true)status = "Single";

if (rdbmarried.Checked == true)status = "Married";

for (int i = 0; i <= lstqualification.Items.Count - 1; i++) {

if (lstqualification.GetSelected(i) == true) {

qualification += lstqualification.Items[i];qualification += " “;}

}

178



message = "User Name = " + name + "\nPassword = " + pwd + "\nAddress = " + address + "\nCountry = " + country + "\nTelephone = " + tel + "\nMobile = " + mobile + "\nGender = " + gender + "\nStatus = " + status + "\nQualification = " + qualification;

try {if (!Directory.Exists(@“C:\Users")) {

Directory.CreateDirectory(@"c:\Users");}string path = @“C:\Users\" + name + ".txt";FileStream fs = new FileStream(path, FileMode.Create);StreamWriter writer = new StreamWriter(fs);writer.WriteLine(message);writer.Close();fs.Close();MessageBox.Show("Data added in file");fs = new FileStream(path, FileMode.Open);StreamReader reader = new StreamReader(fs);rtbdisplay.Text = reader.ReadToEnd();rtbdisplay.Visible = true;

179



reader.Close();fs.Close(); }catch (Exception ex) {

MessageBox.Show(ex.Message);} }

private void btnclear_Click(object sender, EventArgs e) {

txtuname.Clear();txtpwd.Clear();txtaddress.Clear();cmbcountry.Text = "";rdbmale.Checked = false;rdbfemale.Checked = false;rdbsingle.Checked = false;rdbmarried.Checked = false;chktel.Checked = false;chkmobile.Checked = false;txttel.Clear();

txttel.Enabled = false;txtmobile.Clear();txtmobile.Enabled = false;lstqualification.Refresh();rtbdisplay.Clear();rtbdisplay.Visible = false;chkusers.Checked = false; }

private void chkusers_CheckedChanged (object sender, EventArgs e) {

if (chkusers.Checked == true) {lstusers.Items.Clear();lstusers.Visible = true;string path = @"c:\users";string[] users = Directory.GetFiles(path);for (int i = 0; i < users.Length; i++) {

lstusers.Items.Add(users[i]); }}else

lstusers.Visible = false; }

180



private void lstusers_SelectedIndexChanged(object sender, EventArgs e) {try {

string filename = lstusers.Text;FileStream fs = new FileStream(filename, FileMode.Open);StreamReader reader = new StreamReader(fs);rtbdisplay.Text = reader.ReadToEnd();rtbdisplay.Visible = true;reader.Close();fs.Close();

}catch (Exception ex) {

MessageBox.Show(ex.Message);}

}

(Source code: Module11\FileIO\FileIO\Registration.cs)


Module 13. Working with Databases

• OverviewIntroduction to Ado.NetAdo.Net disconnected modelAdo.Net connected ModelData ProvidersDisconnected Database ConnectivityConfiguring Connection String in Config fileConnected Database ConnectivityFilterInsert data using connected architectureCommand BuilderData NavigationMaster – Detail RelationshipStored Procedure

181


Overview (Contd…)

TransactionData RelationSQL Bulk CopyBatch UpdateMultiple Active Result SetReading and writing data to XMLData Independent Provider


Introduction to Ado.Net

• ADO.NET is a set of classes, interfaces for working with data• A system designed for disconnected environments• A programming model with XML support• Use XML as the format for transmitting data from a data

source to DataSet

183

184


ADO.NET Disconnected Model

Connection

Data Adapter

Client Application

Database

DataSet Select Command

Insert Command

Update Command

Delete Command

Provider

DataSet

XML

Connection object which provides a connection to the Data source.

ADO.Net introduces the concept of disconnected data architecture. In traditional data access components, you make a connection to the database system and then interact with it through SQL queries using the connection. The application stays connected to the DB system even when it is not using DB services. This commonly wastes the valuable and expensive database resource as most of the time applications only query and view the persistent data. ADO.Net solves this problem by managing a local buffer of persistent data called data set. Your application connects to the database server when it needs to pass some query and then disconnects immediately after getting the result back and storing it in dataset. This design of ADO.Net is called disconnected data architecture.

DataAdapter is the bridge between data source and the DataSet. It fills the data to the DataSet and performs the update.

The dataset is a in-memory representation of data. It can be considered as a local copy of the relevant portions of the database.

DataAdapeter class take care of when to open the connection and when to close it. We do not require to explicitly maintain the connection object.

For select command we have to call the Fill() method of the DataAdapter class.And for insert, update and delete command we have to call Update() method of the DataAdapterclass.

These methods internally maintain connection object.

185


ADO.NET Connected Model

Connection

Command

Data Reader

Client Application Database

Provider

Connection object which provides a connection to the Data Source.

In the connected environment, it is your responsibility to open and close the database connection. You first establish the database connection, perform the interested operations to the database and when you are done, close the database connection. All the changes are done directly to the database and no local (memory) buffer is maintained.Command takes any SQL statement or Stored Procedure

Data Reader provides Read Only, Forward Only stream of rows from a Data Source.

Three methods to execute the commandExecuteNonQuery()Use for executing query which is not going to return record. E.g. Insert, update, delete, create, drop, stored procedure etc. (returns number of rows affected)

ExecuteReader()Execute the query, and returns one row at a time. Return type is DataReader.

ExecuteScalar()Returns single value Execute the query, and returns the first column of the first row in the result set returned by the query. Extra columns or rows are ignored. Return type is Object.

In the connected model in our code we have to maintain the connection object. Before executing any query, first we require to open the connection and after executing the query we have to close the connection. Till the time you will not close the connection the resource is in use and you cannot execute another query using the same connection object.


Date Providers (NameSpaces)

• System.Data• System.Data.OleDb• System.Data.SqlClient• System.Data.OracleClient• System.Data.Common

•System.DataDataSet, DataTable, DataColumn, DataRow, DataRelation, DataView etc.

•System.Data.OleDbCan be used with all the databases like Ms Access, Ms SQL Server,

Oracle, Sybase, DB2 etc.

•System.Data.SqlClientUsed only with Ms SQL Server 7.0 and above versionWill give the support foe the features of Ms SQL Server database like SQL

Bulk Copy etc.Support the Data Type of Ms SQL Server Database

•System.Data.OracleClientUsed only with Oracle databaseSupport the Data Type of Oracle Database like CLOB, BLOB, BFILE etc.

•System.Data.CommonIt support a;; the data providers mention above. The classes in this provider are integrated to give a support to write the

code that will work with all .Net Framework data providers.

186

187


Disconnected Database Connectivity with Different Databases

188


Disconnected Connectivity with Ms SQL Server

• Add the following namespace in the program• using System.Data.SqlClient;Write code for Ms SQL Server Button Click Eventtry {

SqlConnection conn = new SqlConnection(@"server=.\sa1; database=Northwind; integrated security=true;");

string sql = "select * from products";SqlDataAdapter adp = new SqlDataAdapter(sql, conn);DataSet ds = new DataSet();adp.Fill(ds, "products");dataGridView1.DataSource = ds.Tables["products"];



Disconnected connectivity with MS Access Add the following namespace in the programusing System.Data.OleDb;Write code for Ms Access Button Click Eventtry {

OleDbConnection conn = new OleDbConnection (@"provider=Microsoft.Jet.OLEDB.4.0; data source = C:\Northwind.mdb");

string sql = "select * from customers";OleDbDataAdapter adp = new OleDbDataAdapter(sql, conn);DataSet ds = new DataSet();adp.Fill(ds, "customers");dataGridView1.DataSource = ds.Tables["customers"];



Disconnected connectivity with MS AccessAdd the following namespace in the programusing System.Data.OracleClient;Write code for Oracle button Click Eventtry {

OracleConnection conn = new OracleConnection("data source=<oracelservicename>; user id=<username>; password=<password>;");string sql = "select * from emp";OracleDataAdapter adp = new OracleDataAdapter(sql, conn);DataSet ds = new DataSet();adp.Fill(ds, "emp");dataGridView1.DataSource = ds.Tables["emp"];



189


Configuring Connection String in .config File• To add the App.config file in your project click menu

Project -> Add New ItemFrom left hand side select “General” option and from the write hand side select “Application Configuration File”.Do not change the name of this file.Click on “Add” button to add the file in your project.

•Config is a XML file.•if you have to change server name ,database name etc in connection string then you have to make changes in only .config file and not on each and every Forms.•you can also add more than one connection string in config file.•To access the connection string from the config file, first you have to add the reference to the System.Configuration namespace in your project. •use the System.Configuration namespace in every C# files, where you want to use the connection string from the config file.

190


Configuring Connection String in .config File (contd…)

• Write the connection string in the confilg file within connectionStrings element

<?xml version="1.0" encoding="utf-8" ?><configuration>

<connectionStrings><add name="NorthwindConnStr"

connectionString="server=.\sa1;database=Northwind;integrated security=true" providerName="System.Data.SqlClient" />

</connectionStrings></configuration>


Using Connection String in C# file

using System.Data.SqlClient;using System.Configuration;

string connstr = ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;SqlConnection conn = new SqlConnection(connstr);

191

192


Display Data using Connected Architecture

string connstr = ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;SqlConnection conn = new SqlConnection(connstr);string sql = "select * from categories";SqlCommand cmd = new SqlCommand(sql, conn);conn.Open();SqlDataReader reader = cmd.ExecuteReader();DataTable table = new DataTable();table.Load(reader);conn.Close();dataGridView1.DataSource = table;

(Source code: Module12\DatabaseApplication\DatabaseApplication\02Connected.cs)

193


Apply Filter on DataSet

(Source code: Module12\DatabaseApplication\DatabaseApplication\03Filter.cs)

DataSet data is the in memory data. After we retrive the data in dataset, we can apply the filter on it and display the specific data to the users.

For this there are 2 methods1] Select() method of the DataTable class and 2] DataView class object with RowFilter Property

194


Apply Filter on DataSet (Contd…)

• Declare the 2 class level variableint catid = 0;DataSet ds;• Form Load Eventstring connstr =

ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;SqlConnection conn = new SqlConnection(connstr);SqlDataAdapter adp = new SqlDataAdapter("select * from Categories", conn);ds = new DataSet();adp.Fill(ds, "Categories");adp = new SqlDataAdapter("Select * from Products", conn);adp.Fill(ds, "Products");lstcategory.DisplayMember =

ds.Tables["Categories"].Columns["CategoryName"].ToString();lstcategory.ValueMember = ds.Tables["Categories"].Columns["CategoryID"].ToString();lstcategory.DataSource = ds.Tables["Categories"];


195


Apply Filter on DataSet (Contd…)

• ListBox SelectedIndexChanged Eventif (lstcategory.SelectedIndex >0 && lstcategory.SelectedValue != null) {

catid = (int) lstcategory.SelectedValue ;}• View Button Click EventDataView view = ds.Tables["Products"].DefaultView;view.RowFilter="categoryid=" + catid;dataGridView1.DataSource = view;

196


Apply Filter on DataSet – DataTable Select() Method

• select button click eventlstselect.Items.Clear();DataRow[] row = ds.Tables["Products"].Select("categoryid=" + catid);if (row.Length > 0) {

for (int i = 0; i < row.Length; i++) {lstselect.Items.Add(row[i]["productName"]);

}}


197


Insert data using Connected Architecture

198


Insert data using Connected Architecture Codestring connstr =

ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;SqlConnection conn = new SqlConnection(connstr);string sql = "Insert into products (productname, unitprice) values (@pname, @price)";SqlCommand cmd = new SqlCommand(sql, conn);cmd.Parameters.AddWithValue("@pname", txtpname.Text);cmd.Parameters.AddWithValue("price", decimal.Parse(txtup.Text));conn.Open();int feedback = cmd.ExecuteNonQuery();conn.Close();MessageBox.Show(feedback + " record inserted");cmd.CommandText = "select productid, productname, unitprice from products where productid >77";conn.Open();SqlDataReader reader = cmd.ExecuteReader();DataTable table = new DataTable();table.Load(reader);conn.Close();dataGridView1.DataSource = table;

199


Stored Procedure

(Source code: Module12\DatabaseApplication\DatabaseApplication\08spin.cs)

200


Stored Procedure (Contd…)

• Write the following stored procedure in the MS SQL Server

create proc InsertData (@prodname varchar(20), @unitprice numeric(10,2)) as begin transaction

insert into products (productname, unitprice) values(@prodname, @unitprice)

Commit transaction

• Code for the Insert Button Clickstring connstr =

ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;SqlConnection conn = new SqlConnection(connstr);


201


Stored Procedure (Contd…)

SqlCommand cmd = new SqlCommand ("Insertdata", conn);cmd.CommandType = CommandType.StoredProcedure;cmd.Parameters.AddWithValue("@prodname", txtpname.Text );cmd.Parameters.AddWithValue("@unitprice", txtup.Text);conn.Open();int feedback = cmd.ExecuteNonQuery();conn.Close();MessageBox.Show(feedback + " record inserted");txtpname.Clear();txtup.Clear();conn.Open();cmd = new SqlCommand("select * from products where productid>77",conn);SqlDataReader reader = cmd.ExecuteReader();DataTable table = new DataTable();table.Load(reader);conn.Close();dataGridView1.DataSource = table;


202


CommandBuilder for Update Data in Disconnected Architecture

(Source code: Module12\DatabaseApplication\DatabaseApplication\05CommandBuilder.cs)

CommandBuilder - Automatically generates single-table commands that are used to reconcile changes made to a DataSet with the associated database.

Minimum requirement to pass the select command (select query) with command builder object.

When associated with a DataAdapter, the DbCommandBuilder automatically generates the InsertCommand, UpdateCommand, and DeleteCommand properties of the DataAdapter

The SelectCommand must also return at least one primary key or unique column. If none are present, an InvalidOperation exception is generated, and the commands are not generated.

203


Code for update data using CommandBuilder

• Declare Class level membersSqlConnection conn;SqlDataAdapter adp;SqlCommandBuilder cb;DataTable table;

• Write the following code in load event

conn = new SqlConnection(connstr);string sql = "select * from products";adp = new SqlDataAdapter(sql, conn);cb = new SqlCommandBuilder(adp);table = new DataTable();adp.Fill(table);DataColumn[] pk = new DataColumn [1];pk[0] = table.Columns["productid"];table.PrimaryKey = pk;dataGridView1.DataSource = table;


204


Code for update data using CommandBuilder

• Write the following code for the Update button click event

try{

table = (DataTable )dataGridView1.DataSource;adp.Update(table );MessageBox.Show("Data modified in the Database");

}catch (Exception ex)

{MessageBox.Show(ex.Message);

}


205


Data Navigation

(Source code: Module12\DatabaseApplication\DatabaseApplication\06DataNavigation.cs)

206


Data Navigation (Contd…)

• Declare class level memberSqlConnection conn;SqlDataAdapter adp;SqlCommandBuilder cb;DataSet ds;BindingManagerBase bm;int pid, flag;

void Display(){

txtpid.Text = ds.Tables["products"].Rows[bm.Position]["productid"].ToString();txtpname.Text =

ds.Tables["products"].Rows[bm.Position]["productname"].ToString();txtup.Text = ds.Tables["products"].Rows[bm.Position]["unitprice"].ToString();lblrecno.Text = bm.Position + 1 + " / " + bm.Count;

}


207



• Code for load event

string connstr = ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;conn = new SqlConnection(connstr);string sql = "select productid, productname,unitprice from products";adp = new SqlDataAdapter(sql, conn);cb = new SqlCommandBuilder(adp);ds = new DataSet();adp.Fill(ds, "products");DataColumn[] pk = new DataColumn[1];pk[0] = ds.Tables["products"].Columns["productid"];ds.Tables["products"].PrimaryKey = pk;bm = this.BindingContext[ds, "products"];bm.Position = 0;Display();


208



• First Buttonbm.Position = 0Display()

• Next Buttonbm.Position += 1Display()

• Prior Buttonbm.Position -= 1Display()

• Last Buttonbm.Position = bm.Count - 1Display()


209



• Add Buttontxtpid.Clear();txtpname.Clear();txtup.Clear();flag = 1;btnsave.Enabled = true;

• Edit Buttonpid =int.Parse ( txtpid.Text);flag = 2;btnsave.Enabled = true;

• Delete ButtonDialogResult result = MessageBox.Show("Are you sure, you want to delete the record?", "Delete Box", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2);

if (result == DialogResult.Yes){

MessageBox.Show("Click save button to delete the record");

pid = int.Parse(txtpid.Text);flag = 3;btnsave.Enabled = true;

}


210



• Save ButtonDataRow dr;if (flag == 1) { //Add

dr = ds.Tables["products"].NewRow();dr["productid"] = 0;dr["productname"] = txtpname.Text;dr["unitprice"] = decimal.Parse(txtup.Text);ds.Tables["products"].Rows.Add(dr);

}

else if (flag == 2) { //Editdr = ds.Tables["products"].Rows.Find(pid);if (dr != null) {

dr.BeginEdit();dr["productid"] = pid;dr["productname"] = txtpname.Text;dr["unitprice"] = decimal.Parse(txtup.Text);dr.EndEdit();} }

else if (flag == 3) { //Deletedr = ds.Tables["products"].Rows.Find(pid);if (dr != null) {

dr.Delete();}

}

adp.Update(ds, "products");MessageBox.Show("Data modified");ds.Clear();adp.Fill(ds, "products");bm.Position = 0;Display();flag = 0;btnsave.Enabled = false;


211



• Concurrency Checkcatch (Exception ex) {

MessageBox.Show(ex.Message);if (ds.HasErrors) {

foreach(DataTable table in ds.Tables) {if (table.HasErrors) {

foreach (DataRow row in table.Rows) {if (row.HasErrors) {

MessageBox.Show("Table : " + table.TableName + "\n Row : " + row["productid"].ToString() + "\n" + row.RowError, "Error Box");

row.ClearErrors();row.RejectChanges();

}}

}}

}}


212



• Exit ButtonApplication.Exit();

• Find Button

_06FindProduct frm = new _06FindProduct();frm.ShowDialog();int productid = frm.prodid;//MessageBox.Show(productid.ToString());if (productid > 0) {

DataRow dr = ds.Tables["products"].Rows.Find(productid);if (dr != null)

MessageBox.Show("Product ID : " + dr["productid"] + "\nProduct Name : " + dr["productname"] + "\nUnit Price : " + dr["unitprice"], "Display Box");

elseMessageBox.Show("Record not found", "Display Box");


213



public _06FindProduct() {InitializeComponent();

}public int prodid;private void btnsubmit_Click(object sender, EventArgs e) {

if (txtprodid.Text == "")prodid = 0;

elseprodid = int.Parse (txtprodid.Text);

this.Close();}

(Source code: Module12\DatabaseApplication\DatabaseApplication\06FindProduct.cs)

214


Master Detail Relationship

(Source code: Module12\DatabaseApplication\DatabaseApplication\07MasterDetail.cs)

215


Master Detail Relationship (Contd…)

Class level declarationSqlConnection conn;SqlDataAdapter adp;SqlCommandBuilder cb;DataSet ds;BindingManagerBase bm;

void Display() {txtcatid.Text =

ds.Tables["categories"].Rows[bm.Position]["categoryid"].ToString();txtcatname.Text =

ds.Tables["categories"].Rows[bm.Position]["categoryname"].ToString();lblrecno.Text = bm.Position + 1 + " / " + bm.Count;int catid = int.Parse(txtcatid.Text);DataView view = ds.Tables["products"].DefaultView;view.RowFilter = "categoryid=" + catid;dataGridView1.DataSource = view;

}


216



Form Load Event

string connstr = ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;

conn = new SqlConnection(connstr);string sqlcategory = "select categoryid, categoryname from categories order by

categoryid";string sqlproduct = "select productid, productname,unitprice, categoryid from

products";adp = new SqlDataAdapter(sqlcategory, conn);ds = new DataSet();adp.Fill(ds, "categories");SqlCommand selectcmd = new SqlCommand(sqlproduct, conn);adp.SelectCommand = selectcmd ;adp.Fill(ds, "products");bm = this.BindingContext[ds, "categories"];bm.Position = 0;Display();


217



• First Buttonbm.Position = 0;Display();

• Previous Buttonbm.Position = bm.Position + 1;Display();

• Next Buttonbm.Position = bm.Position + 1;Display();

• Last Buttonbm.Position = bm.Count - 1;Display();


218


Stored Procedure with Out Parameter

• Write the following stored procedure in the MS SQL Server

create proc TotalProduct (@catid int, @count int output) asselect @count=count(productid) from products where Categoryid = @catid

(Source code: Module12\DatabaseApplication\DatabaseApplication\09spout.cs)

219


Stored Procedure with Out Parameter (Contd…)

• Form Load event populate the list box


SqlConnection conn = new SqlConnection(connstr);string sql = "select categoryid, categoryname from categories order by categoryid";SqlDataAdapter adp = new SqlDataAdapter(sql,conn);DataSet ds = new DataSet();adp.Fill(ds,"categories");lstcategory.DisplayMember = ds.Tables["categories"].Columns["categoryname"].ToString();lstcategory.ValueMember = ds.Tables["categories"].Columns["categoryid"].ToString();lstcategory.DataSource = ds.Tables["categories"];


220


Stored Procedure with Out Parameter (Contd…)

• Type the following code in the ListBoxSelectedIndexChanged event


SqlConnection conn = new SqlConnection(connstr);SqlCommand cmd = new SqlCommand("TotalProduct", conn);cmd.CommandType = CommandType.StoredProcedure;cmd.Parameters.AddWithValue("@catid", int.Parse(lstcategory.SelectedValue.ToString() ));cmd.Parameters.Add("@count", SqlDbType.Int);cmd.Parameters[1].Direction = ParameterDirection.Output;conn.Open();cmd.ExecuteNonQuery();conn.Close();lblresult.Text = "Total Product for catgory " + lstcategory.SelectedValue.ToString() + " = " + cmd.Parameters[1].Value.ToString();


221


Transaction

int result1, result2;


SqlConnection conn = new SqlConnection(connstr);conn.Open();

(Source code: Module12\DatabaseApplication\DatabaseApplication\10Transaction.cs)

222


Transaction (Contd…)

cmd = conn.CreateCommand();cmd.Connection = conn;cmd.CommandText = "insert into products (productname, unitprice) values

('Ipod',25000)";MyTransaction = conn.BeginTransaction();cmd.Transaction = MyTransaction;result1 = cmd.ExecuteNonQuery();cmd.CommandText = "update products set unitprice=0 where productid=80";result2 = cmd.ExecuteNonQuery();if (result1 > 0 && result2 > 0) {

MyTransaction.Commit();MessageBox.Show("Transaction saved, Data modified");

}else {

MyTransaction.Rollback();MessageBox.Show("Transaction Rollback");

}

(Source code: Module12\DatabaseApplication\DatabaseApplication\10Transaction.cs)

223


DataRelation

(Source code: Module12\DatabaseApplication\DatabaseApplication\11DataRelation.cs)

224


DataRelation (Contd…)

• Form Load Eventdecimal total;string connstr =

ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;SqlConnection conn = new SqlConnection(connstr);SqlDataAdapter adpcategory = new SqlDataAdapter("select * from Categories",

conn);SqlDataAdapter adpprod = new SqlDataAdapter("select * from products", conn);DataSet ds = new DataSet();adpcategory.Fill(ds, "categories");adpprod.Fill(ds, "products");ds.Relations.Add("category", ds.Tables["categories"].Columns["categoryid"],

ds.Tables["products"].Columns["categoryid"]);


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DataRelation (Contd…)

foreach (DataRow catrow in ds.Tables["categories"].Rows) {total = 0;lstrelation.Items.Add("CategoryID = " + catrow["categoryid"] + " " + "Category Name = " + catrow["categoryName"]);

lstrelation.Items.Add("-------------------------------");foreach (DataRow prodrow in catrow.GetChildRows("category")) {

lstrelation.Items.Add("Productname = " + prodrow["productname"] + " " + "unitPrice = " + prodrow["unitprice"]);

total += decimal.Parse(prodrow["unitprice"].ToString());}

lstrelation.Items.Add("-------------------------------------------------");lstrelation.Items.Add("Total = " + total);lstrelation.Items.Add("-------------------------------------------------");

}



Module 14. Data Bound Control

• OverviewPopulating DataGridView Control using WizardPopulating ListBox Control using WizardBinding Navigator

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Populating DataGridView Control using Wizard

• Add DataGridView Control from the data menu• Click on the smart tag• Click on Choose Data Source Drop Down arrow

(Source code: Module 13\DataBoundControl\DataBoundControl\01DataGridControl.cs)

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Populating DataGridView Control using Wizard (Contd…)

• Click on Add Project Data Source

• Select Database and click Next option


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• Click New Connection Button and specify the name of the SQL Server, Authentication and Database.

• Click on Test Connection button.• If you get the message Test Connection Succeeded then click

on OK button.


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• Save the connection String in Application Configuration file• Click Next Button


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• Select “Categories” table from the list and click “Finish”button


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• Display the data in grid


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Populating ListBox Control using Wizard

• Add ListBox from the Common Controls• Click on smart option• Check “Use data bound items”

(Source code: Module 13\DataBoundControl\DataBoundControl\02ListBoxControl.cs)

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Populating ListBox using Wizard (Contd…)

• Select Data Source option• Specify Display Member and Value Member options


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• Add the Label and name the label as lblcatid.• Write the following code in the listbox SelectedIndexChanged

event

private void listBox1_SelectedIndexChanged(object sender, EventArgs e){

if (listBox1.SelectedValue != null)lblcatid.Text = listBox1.SelectedValue.ToString();

}


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• Run the Form• Display Member property is used for display the column in

the ListBox.• When we select the option from the ListBox it will display

the Value Member.


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Binding Navigator

• Add Binding Source Control from the Data Tab.• Go to Property window and specify DataSource Property.• Add 2 Labels and 2 Textboxes• Add Binding Navigator Control from Data Tab.• Go to Property window and specify BindingSource Property

as BindingSource1• DataMember Property as Categories• Select the txtcatid TextBox and assign the DataBinding -

Text property as Categoryid• Select the txtcatname TextBox and assign the DataBinding -

Text property as CategoryName

(Source code: Module 13\DataBoundControl\DataBoundControl\03Navigator.cs)

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Binding Navigator (Contd…)

• Run and Test the Program

(Source code: Module 13\DataBoundControl\DataBoundControl\03Navigator.cs)


Module 15. DotNet Framework & Assembly

• Overview.Net FrameworkAssemblyType of AssemblyCreate Class Library Create Test ApplicationCreating Shared AssemblyViewing the Manifest FileProcess of compiling and executing managed code

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Assembly

AssemblyManifest

ModuleMetadata

MSIL

Types TypesTypesTypes

An assembly is a single deployable unit that contains all the information about the implementation of classes, structure, interfaces, enum and delegates. An assembly stores all the information about itself. The information is called metadata, which includes the name and version number of the assembly, security information, information about the dependencies, and a list of the files that constitute the assembly. Assembly is a logical EXE or DLL.An assembly consists of manifest, module and type.Manifest – is the descriptor of the assembly.Module – is either a DLL or EXE.Type – can be a class, interface, structure, enum, delegates that contains data and logic.

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Types of Assembly

• Private Assembly• Shared Assembly

Private AssemblyA private assembly is deployed and used exclusively with a single name.A private assembly is referenced by its simple nameThe simple name is defined in the assembly’s metadata.When you refer to private assembly , it get copied into the project which is referring to this assembly.

Shared AssemblyShared assembly is also known as Strong Named AssemblyIt gives support to versioning and security of assemblyStrong named assembly will have unique identificationWhen you refer to shared assembly , it will not create the local copy of this assembly. It always refer to the location from where you have included the reference.

Identity consist of•Simple Text Name•Version Number•Culture Information•Public Key•Digital Signature


Creating Shared Assembly (Contd…)

• Adding the dll file in GAC folder(C:\WINDOWS\Microsoft.NET\assembly\GAC_MSIL)

• Start MS Visual Studio Command Prompt and go to the folder where you have stored your dll file.

(Start – Program – Microsoft Visual Studio 2010 – Visual Studio Tools –Visual Studio 2010 Command Prompt )

• Generate strong name key.Sn -k key.snk calc.snk

• Type the following command at the command prompt• gacutil –i calculatorlib.dll• This command will register the assembly in GAC• Now when you add the reference of the assembly into your

application, it will not create the local copy of assembly, it will maintain the reference to the folder from where you are adding the assembly.

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Viewing Manifest File

Intermediate Language Disassembler (ILDASM)ILDASM is a tool for viewing the contents of assembly.Each assembly has a single manifest file which contains metadata.Go to Microsoft Visual Studio command Prompt and type ILDASM or go to start – program –Microsoft Windows SDK V6.OA – Tools – IL DisassemblerSelect File menuClick OpenSelect exe or dll file for which you want to see IL code


Module 16. Delegate

• OverviewUnderstanding DelegateSingleCast DelegateMultiCast DelegateAnonymous Method

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Understanding Delegate

• Declaring and invoking Delegate involves 4 stepsDelegate declarationdelegate returntype Name ([parameters]) Declare Delegate methodReturntype Name ([parameters]) Delegate instantiationdelegatename instancename = new delegatename(methodname)Delegate invocationInstancename(parameters value)

• Use of DelegateEventsThreadsAsynchronous Application

Features of Delegate

•Delegate is one of the type which we can declare within the Namespace.•Delegates are termed as function pointers.•Delegates contain the address of the method that is to be executed.•Signature of delegate and method signature should be identical.•Delegates act as middle layer to communicate the event occurred to the system.•There are two types of delegates Singlecast and multicast.

Singlecase delegate can hold and invoke single methodMulticast delegate can hold and invoke multiple methods.

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SingleCast Delegate//Declare Delegatedelegate void DelegateString(string s);delegate int DelegateCube(int number);class _01SingleCastDelegate {

//methodpublic static void Greet(string Name) {

Console.WriteLine("Hello..." + Name);}//methodpublic static void Wish(string Name) {

int Hour = System.DateTime.Now.Hour;if (Hour >= 5 && Hour < 12)

Console.WriteLine("Good Morning..." + Name);else if (Hour >= 12 && Hour < 16)

Console.WriteLine("Good Afternoon..." + Name);else if (Hour >= 16 && Hour < 22)

Console.WriteLine("Good Evening..." + Name);else

Console.WriteLine("Good Night..." + Name);}

(Source code: Module 15\DelegateExample\DelegateExample\01SingleCastDelegate.cs)

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SingleCast Delegate (Contd…)

//methodpublic static int NumberCube(int number) {

return number * number * number;}public static void Main() {

//instantiate delegateDelegateString delegateobj1 = new DelegateString(Greet);DelegateString delegateobj2 = new DelegateString(Wish );//Invoke delegatedelegateobj1("Bhavana");Console.WriteLine("-----------------------------------");delegateobj2("Bhavana");Console.WriteLine("=====================================");DelegateCube delegatecubeobj = new DelegateCube(NumberCube);Console.WriteLine("Cube of Number 3 = " + delegatecubeobj(3));Console.ReadLine();

}}

(Source code: Module 15\DelegateExample\DelegateExample\01SingleCastDelegate.cs)

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MultiCast Delegate

delegate void DelegateMultiCast (int value1, int value2);

class _02MultiCastDelegate{

public static void AddNumbers(int number1, int number2){

int total = number1 + number2;Console.WriteLine("Addition of 2 numbers {0}, {1} = {2}", number1,

number2,total);}public static void MultiplyNumbers(int number1, int number2){

int total = number1 * number2;Console.WriteLine("Multiplication of 2 numbers {0}, {1} = {2}", number1,

number2, total);}

(Source code: Module 15\DelegateExample\DelegateExample\02MultiCastDelegate.cs)

Using multicast delegate you can call more then one method through single delegate instance.It will successively call each method in order.The delegate signature should return a void, otherwise, you would only get the result of the last invoked method.If one of the method invoked by the delegate throws an exception, the execution stops.

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MultiCast Delegate (Contd…)

public static void Power(int number1, int number2) {int total=1;for (int i = 1; i <= number2; i++){

total = total * number1;}Console.WriteLine("Power of number {0}, {1} = {2}", number1, number2, total);

}

public static void Main() {DelegateMultiCast Multicastobj=null;Multicastobj += new DelegateMultiCast(AddNumbers);Multicastobj += new DelegateMultiCast(MultiplyNumbers);Multicastobj += new DelegateMultiCast(Power);Multicastobj(5,3);Console.ReadLine();

}}

(Source code: Module 15\DelegateExample\DelegateExample\02MultiCastDelegate.cs)


Event

• Provides notifications to clients when something interesting happens.

• Events are declared using delegates.


Events continued…delegate void MyEventHandler();

class MyEvent {public event MyEventHandler SomeEvent;public void OnSomeEvent() {

if (SomeEvent != null)SomeEvent();

} }class Program {static void handler() {

Console.WriteLine("Event occurred");} static void Main(string[] args) {

MyEvent evt = new MyEvent();evt.SomeEvent += handler;evt.OnSomeEvent(); } }

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Anonymous Methoddelegate void DelegateAnonymous(int value1, int value2);class _03AnonymousMethod {

public static void Main() {DelegateAnonymous obj = delegate(int number1, int number2){

try {int Total = number1 / number2;Console.WriteLine("Division of {0} / {1} = {2}", number1, number2, Total);

}catch (DivideByZeroException ex) {

Console.WriteLine(ex.Message);}

};

obj(10, 2);Console.ReadLine();

}}

(Source code: Module 15\DelegateExample\DelegateExample\03AnonymousMethod.cs)

A method must exist for the delegate to work. However, another way to use the delegate is “Anonymous Method”.An anonymous method is a block of code that is used as the parameter for the delegate.The benefit of the anonymous method is to reduce the code. You do not have to define a method just ot use it with delegate.With anonymous method code does not perform faster. The compiler will defines a method, which has an automatically assigned name, which we do not need to know.


Module 17. Threads

• OverviewUnderstanding ThreadsCreating, executing and terminating threadsParametizeThreadStart DelegateThread PrioritiesSynchronization among threads

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Understanding Thread

• Thread is a line of execution.• Series of steps executed at a time is known as a Thread. • Import System.Threading namespace for all the Thread

Program.

Initialize Balance

Call Deposit Method

Increment Balance

Print Balance

Each stream of execution is called a thread. Multithreading is used to divide lengthy tasks into different segments that would otherwise abort programs. Threads are mainly used to utilize the processor to a maximum extent by avoiding it's idle time. Threads in DotNet are based on the namespace System.Threading.


MultiThreading

• Execution of such steps by different tellers can be considered as multi-threading in a computer jargon.

Initialize Balance

Call Deposit Method

Increment Balance

Print Balance

Initialize Balance

Call Deposit Method

Increment Balance

Print Balance

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Thread State

Wait/Sleep/Join

Unstarted Running Abort Requested

Stopped

Start

Thread Blocks

Thread Unblocks

Abort

Abort

Thread Ends

Thread Ends

Specifies the execution states of a thread.

Unstarted – The Start() method has not been invoked on the thread

Running – The thread has been started, it is not blocked.

Wait / Sleep / Join – The thread is blocked. This could be the result of calling Sleep() or Join() or requesting a lock Monitor.Enter() or Monitor.Wait()

Abort Requested – the Abort() method has been invoked on the thread.

Stopped – the thread has stopped.

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Creating Threadvoid Runthread_Task() {

for (int i = 1; i <= 10; i++) {Console.WriteLine("\tMsg #{0} from secondary thread", i);

}}

void RunThread() {Thread t = new Thread(new ThreadStart(Runthread_Task));//run the new threadt.Start();//print some message to the console windowfor (int i = 1; i <= 10; i++) {

Console.WriteLine("Msg #{0} from Main Thread", i); }//t.Abort();//t.Join();Console.WriteLine("End of Main Thread Program");

}

(Source code: Module 16\ThreadApplication\ThreadApplication\01Thread.cs)Methods of Thread

StartStart the ThreadChange the ThreadState to Running modeThreadState specifies the execution states of a Thread

SleepBlock the current Thread for the specified number of milliseconds.

AbortTerminate the Thread

JoinBlock the calling Thread until a thread terminates or complete the task.

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Creating Thread (Contd…)

static void Main(string[ ] args) {_01Thread obj = new _01Thread();obj.RunThread();Console.ReadLine();

}

(Source code: Module 16\ThreadApplication\ThreadApplication\01Thread.cs)

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ParameterizedThreadStart Delegatevoid RunParameterizedThread_Task(Object obj) {

for (int i = 1; i <= (int)obj; i++) {

Console.WriteLine("Msg #{0} from secondary thread", i);}

}

void RunparametizedThread() {Thread t = new Thread(new ParameterizedThreadStart

(RunParameterizedThread_Task ));t.Start(20);for (int i = 1; i <= 20; i++){

Console.WriteLine("Msg #{0} from Main Thread", i);}t.Join();

}

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ParameterizedThreadStart Delegate (Contd…)


_02ThreadParameter obj = new _02ThreadParameter();obj.RunparametizedThread();Console.WriteLine("Thread Program over");Console.ReadLine();

}

(Source code: Module 16\ThreadApplication\ThreadApplication\02ThreadParameter.cs)

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Thread Priority

• ThreadPriority EnumerationAbove NormalBelow NormalHighestLowestNormal

• Default priority for all thread is Normal

Threads are scheduled for execution based on their priority. It determines the order of thread execution. It can be very with each Operating System.

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Thread Priority (Contd…)

public long count;

public void StartCount() {while (true) {

count += 1;}

}

(Source code: Module 16\ThreadApplication\ThreadApplication\03Priority.cs)

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Thread Priority (Contd…)

public static void Main() {_03Priority obj1 = new _03Priority();Thread t1 = new Thread(new ThreadStart(obj1.StartCount));t1.Priority = ThreadPriority.Lowest;_03Priority obj2 = new _03Priority();Thread t2 = new Thread(new ThreadStart(obj2.StartCount));t2.Priority = ThreadPriority.Highest;t1.Start();Thread.Sleep(1);t2.Start();Thread.Sleep(1);t1.Abort();t2.Abort();Console.WriteLine("High Priority Thread Clicks : " + obj2.count);Console.WriteLine("Low Priority Thread Clicks : " + obj1.count);Console.ReadLine();

}

(Source code: Module 16\ThreadApplication\ThreadApplication\03Priority.cs)


Creating Multiple Thread

• In this process the last recorded transaction updates the balance.

Teller1Teller2

File cabinets

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Multiple Thread

int AccNo;string Name;float Bal;

public float Balance{

get { return Bal; }private set { Bal = value; }

}public _04SavingMultiThread(int AccNo, string Name, float Bal){

this.AccNo = AccNo;this.Name = Name;this.Bal = Bal;

}

(Source code: Module 16\ThreadApplication\ThreadApplication\04SavingMultiThread.cs)

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Multiple Thread (Contd…)

public void Deposit(float amt){

Bal = Bal + amt;Console.WriteLine("Balance after deposit = " + Bal.ToString());

}public void Withdraw(float amt){

Bal = Bal - amt;Console.WriteLine("Balance after withdraw = " + Bal.ToString());

}public void Transaction(object amt){

string ThreadName = Thread.CurrentThread.Name;Console.WriteLine("Depositing amount by " + ThreadName);Deposit((float)amt);Withdraw((float)amt);Console.WriteLine("==================================");

}


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Multiple Thread (Contd…)

public static void Main(){

_04SavingMultiThread s1 = new _04SavingMultiThread (101, "Bhavana", 1000f);Thread thread1 = new Thread(new ParameterizedThreadStart(s1.Transaction));Thread thread2 = new Thread(new ParameterizedThreadStart(s1.Transaction));Thread thread3 = new Thread(new ParameterizedThreadStart(s1.Transaction));thread1.Name = "Thread 1";thread2.Name = "Thread 2";thread3.Name = "Thread 3";thread1.Start(500f);thread2.Start(500f);thread3.Start(500f);Console.ReadLine();

}



Thread Synchronization

• This type of locking tells when to use that filing cabinet and when not to.

Teller2

Wait until I am Finished !!!

Teller1

File cabinets

Synchronized specifies that the method can be executed by only one thread at a time.

We can either use method synchronization or object synchronization (Block synchronization)

For method synchronization we can use the attribute

[MethodImpl(MethodImplOptions.Synchronized )]

before the method declaration which is coming from the namespaceSystem.Runtime.ComillerServices

For object synchronization we can use either the lock() method or Monitor class.

The Monitor class grant a lock for an object.

Lock() method internally use the Monitor class only.

Best practice is to minimize the code inside synchronized blocks because they prevent concurrent threads from executing - losing any advantage of multi-threaded applications. Synchronized blocks help let those portions of a method that do not access shared resources to be run simultaneously while still keeping those parts that need to be shared thread-safe.

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Thread Synchronization (Contd…)

• synchronization provides a lock on the resource that is shared among threads and makes a thread wait until the other thread finishes the job with the resource.

Object lockBalance = 5000

Sub Deposit (byval amt as Decimal) A synchronized transaction

Thread@1 Thread@2 Thread@3

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public void Transaction(object amt){

Monitor.Enter(this);string ThreadName = Thread.CurrentThread.Name;Console.WriteLine("Depositing amount by " + ThreadName);Console.WriteLine("Intial Balance = " + Balance);Deposit((float)amt);Withdraw((float)amt);Console.WriteLine("==================================");Monitor.Exit(this);

}

(Source code: Module 16\ThreadApplication\ThreadApplication\05SavingSynchronizee.cs)

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public static void Main() {_05SavingSynchronize s1 = new _05SavingSynchronize(101, "Bhavana", 1000f);Thread thread1 = new Thread(new ParameterizedThreadStart(s1.Transaction));Thread thread2 = new Thread(new ParameterizedThreadStart(s1.Transaction));Thread thread3 = new Thread(new ParameterizedThreadStart(s1.Transaction));thread1.Name = "Thread 1";thread2.Name = "Thread 2";thread3.Name = "Thread 3";thread1.Start(500f);thread2.Start(500f);thread3.Start(500f);Console.ReadLine();

}

(Source code: Module 16\ThreadApplication\ThreadApplication\05SavingSynchronizee.cs)


Thread pool

• Collection of threads• Performs a number of tasks in background process.• Primary thread leaves free to perform other tasks

asynchronously.

Thread pools are often employed in server applications. Each incoming request is assigned to a thread from the thread pool, so the request can be processed asynchronously, without tying up the primary thread or delaying the processing of subsequent requests.

Once a thread in the pool completes its task, it is returned to a queue of waiting threads, where it can be reused. This reuse enables applications to avoid the cost of creating a new thread for each task.

Thread pools typically have a maximum number of threads. If all the threads are busy, additional tasks are placed in queue until they can be serviced as threads become available.

You can implement your own thread pool, but it is easier to use the thread pool provided by the .NET Framework through the ThreadPool class.

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Module 18. Introduction to Web Services

• OverviewOverview of Web ServicesCreating and Testing Web ServiceConsuming Web Service

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Definition

• XML Web Service is a programmable logic accessible by standard web protocols

Allow applications to send and receive information across the internetLanguage and Platform independent

A web service exposes a number of methods that provide functionality that can be used by one or more applications, regardless of the programming languages, operating systems and hardware platforms used to develop them.

The methods that provide such functionality are called web methods.

Some of the use of XML Web ServiceAuthentication ServicesWeather ReportsExchange RateStock QuotesEtc.

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Components of Web Services

Client Application Web Service

UDDI Registry

Locate a Web Service

WSDL Document

Describes

Communication through SOAP messages

Web service is comprised of five fundamental components•Delivery Medium – Internet•Delivery Protocol – HTTP•Message Formatting – SOAP (Simple Access Object Protocol)•Service Description – WSDL (Web Service Description Language)•Web Service Publication – UDDI (Universal Description, Discovery and Integration)


Creating Web Services

• Select File – New – Web Site

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Code for Web Services

public class ServiceHello : System.Web.Services.WebService{

[WebMethod]public string HelloWorld() {

return "Hello World";}

}

(Source code: Module 18\WebServiceHello\App_Code\ServiceHello.cs)


Test Web Services

278


Consuming Web Services

• Start Windows Application

279


Add Web Service Reference

• Click on Project Menu – Add Web Reference• Click “Web Service on the local machine”

280


Select the Web Service from the List

281


Create Proxy

• Will display the Web methods available in the web service• Click on “Add Reference” button, which creates the proxy.

Default name is “localhost”

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283


Design Windows Form and write the code

• Add one Button and one Label• Write the following code on button click event• Create the object of proxy class and call the method using

proxy object

localhost.ServiceHello obj = new WebServiceHelloTest.localhost.ServiceHello();lblmsg.Text = obj.HelloWorld();

(Source code: Module 18\WebServiceHelloTest\WebServiceHelloTest\Form1.cs)

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Exchange Rate Web Service Example

(Source code: Module 18\WebServiceExchangeRateTest\WebServiceExchangeRateTest\Form1.cs)

285


XML File for Exchange Rate<?xml version="1.0" encoding="utf-8" ?><ExchangeRate>

<ERate><Country>Usa</Country><Rate>41</Rate>

</ERate><ERate><Country>Uk</Country><Rate>70</Rate>

</ERate><ERate><Country>Japan</Country><Rate>120</Rate>

</ERate></ExchangeRate>

(Source code: Module 18\WebServiceExchangeRate\ExchangeRate.XML)

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Code foe Exchange Rate Web Service

• Web method for getting the names of the country

[WebMethod]public string[] GetCountries(){

DataSet ds = new DataSet();List<string> CountryList = new List<string>();ds.ReadXml(Server.MapPath("Exchangerate.xml"));//DataRow[] row = ds.Tables[0].Select("Country");foreach (DataRow dr in ds.Tables[0].Rows ){

CountryList.Add(dr["Country"].ToString());}return CountryList.ToArray();

}

(Source code: Module 18\WebServiceExchangeRate\App_Code\ServiceExchangeRate.cs)

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Code for Exchange Rate Web Service (Contd…)

• Web method return the exchange rate for the country name passed as parameter

[WebMethod]public decimal GetExchangeRate(string Country) {

DataSet ds = new DataSet();decimal rate;ds.ReadXml(Server.MapPath("Exchangerate.xml"));DataRow[] row =ds.Tables[0].Select("Country='" + Country + "'");if (row != null)

rate =decimal.Parse( row[0]["Rate"].ToString());else

rate = 0;return rate;

}

(Source code: Module 18\WebServiceExchangeRate\App_Code\ServiceExchangeRate.cs)

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Consume Exchange Rate Web Service• Design Windows Form with List Box and Label controls• Write the code in form load event to populate list box with

the name of the countries.

localhost.ServiceExchangeRate obj = new WebServiceExchangeRateTest.localhost.ServiceExchangeRate();

private void Form1_Load(object sender, EventArgs e){

obj = new WebServiceExchangeRateTest.localhost.ServiceExchangeRate();string[] countries = obj.GetCountries();foreach (string str in countries){

lstcountry.Items.Add(str);}

}


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List Box SelectedIndexChanged Event

private void lstcountry_SelectedIndexChanged(object sender, EventArgs e){

int count = lstcountry.SelectedIndex;string country = lstcountry.Items[count].ToString();lblmsg.Text = obj.GetExchangeRate(country).ToString();

}



APPENDIX: Windows Form - II

• OverViewMenuStip ControlContextMenuStrip ControlToolStrip ControlStatusStrip ControlDialog ControlsMDI Application

291


Notepad Example

Menu Strip Tool Strip ContextMenu StripRichTextBox

Status Strip

(Source code: APPENDIX\NotepadApplication\NotepadApplication\Notepad.cs)

Example where we cover the controls likeMenu StripTool StripStatus StripContextMenu Strip - is a short cut menu which get activated when user click with

Right Mouse Button on a specific controlRich Text Box

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Notepad Example (Contd…)

FileStream fs;StreamReader reader;StreamWriter writer;string FileName = null;

private void Form1_Load(object sender, EventArgs e){

statusStrip1.Items[1].Text = DateTime.Now.ToString();}private void timer1_Tick(object sender, EventArgs e){

statusStrip1.Items[1].Text = DateTime.Now.ToString();}


MenuItem StripThe strip is to show menu at the top of the form.

PropertiesName – Menu Control NameTextShort Cut – Key Board short cut

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private void newToolStripMenuItem_Click(object sender, EventArgs e) {WorkArea.Text = "";FileName = null;WorkArea.Focus();

}private void openToolStripMenuItem_Click(object sender, EventArgs e) {

if (openFileDialog1.ShowDialog() == DialogResult.OK) {try {

FileName = openFileDialog1.FileName;fs = new FileStream(FileName, FileMode.Open);reader = new StreamReader(fs);WorkArea.Text = reader.ReadToEnd();reader.Close();fs.Close();


MessageBox.Show(ex.Message);} } }


ToolBar StripIt shows toolbar within the space provided below menu strip. It facilitates accessing

menu items through short cuts.

PropertiesNameItems

Select type as Button and click addNameTextImage

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private void saveToolStripMenuItem_Click(object sender, EventArgs e){

if (FileName == null){

saToolStripMenuItem_Click(sender, e);}else{

fs = new FileStream(FileName, FileMode.Create);writer = new StreamWriter(fs);writer.WriteLine(WorkArea.Text);writer.Close();fs.Close();

}}


Status StripProvides status menu strip at the bottom of the form. It gives meta

information/messages/properties about the task.

PropertiesNameItems

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private void saveasToolStripMenuItem_Click(object sender, EventArgs e) {if (saveFileDialog1.ShowDialog() == DialogResult.OK){

try{

FileName = saveFileDialog1.FileName;fs = new FileStream(FileName, FileMode.Create);writer = new StreamWriter(fs);writer.WriteLine(WorkArea.Text);writer.Close();fs.Close();

}catch (Exception ex){


}}


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private void clearToolStripMenuItem_Click(object sender, EventArgs e){

WorkArea.Text = "";FileName = null;

}private void CuttoolStripMenuItem_Click(object sender, EventArgs e){

WorkArea.Cut();}

private void copyToolStripMenuItem_Click(object sender, EventArgs e){

WorkArea.Copy();}


SaveDialog BoxShows dialog box for saving the information.

PropertiesName Control NameDefaultExt Default extension txtFilter File filter to display in a dialog box e.g. txt

files|*.txt|all files|*.*FilterIndex The index of the file filter selected in the dialog 1

for the first itemInitialDirectory The initial directory for the dialogRestoreDirectory Dialog restore the current directory before closing

True / False

FontDialog BoxShow dialog box for selecting fonts from the list of installed fonts on the platform.

PropertiesName Control NameShowColor Show Color Choice TrueShowApply Show the Apply Button True

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private void pasteToolStripMenuItem_Click(object sender, EventArgs e){

WorkArea.Paste();}

private void undoToolStripMenuItem_Click(object sender, EventArgs e){

WorkArea.Undo();}

private void redoToolStripMenuItem_Click(object sender, EventArgs e){

WorkArea.Redo();}


Color Dialog BoxShows dialog box to select color.

PropertiesName Control NameFullOpen Show the custom color section True

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private void fontToolStripMenuItem_Click(object sender, EventArgs e){

try{

if (fontDialog1.ShowDialog() == DialogResult.OK){

WorkArea.SelectionFont = fontDialog1.Font;WorkArea.SelectionColor = fontDialog1.Color;

}}catch (Exception ex){


}


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private void backgroundColorToolStripMenuItem_Click(object sender, EventArgs e){

try{

if (colorDialog1.ShowDialog() == DialogResult.OK)WorkArea.BackColor = colorDialog1.Color;

}catch (Exception ex){


}

private void exitToolStripMenuItem_Click(object sender, EventArgs e){

Application.Exit();}


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private void toolStripButtonNew_Click(object sender, EventArgs e){

newToolStripMenuItem_Click(sender, e);}

private void toolStripButtonOpen_Click(object sender, EventArgs e){

openToolStripMenuItem_Click(sender, e);}

private void toolStripButtonSave_Click(object sender, EventArgs e){

saveToolStripMenuItem_Click(sender, e);}


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private void toolStripButtonCut_Click(object sender, EventArgs e){

CuttoolStripMenuItem_Click(sender, e);}private void toolStripButtonCopy_Click(object sender, EventArgs e){

copyToolStripMenuItem_Click(sender, e);}

private void toolStripButtonPaste_Click(object sender, EventArgs e){

pasteToolStripMenuItem_Click(sender, e);}


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MDI Application

• Three steps for creating MDI ApplicationCreate a Parent FormCreate a Child FormCall Child Form from a Parent Form

Single Document Interface (SDI) only one document is visible at a time, e.g., Notepad.

Multiple Document Interface Application (MDI) allows to display multiple document at the same time, with each document displayed in its own window, e.g., Microsoft Word.

303


MDI Application Example

(Source code: APPENDIX\MdiApplication\MdiAppliation)

304


MDI Application Example (Contd…)

• Start New Project• Create Parent Form• Set IsMdiContainer Property of the Parent Form to True• Add Menu Item• Add Child Form• Add RichTextBox on Child Form

• Parent Form class level declarationint count=0;

305


MDI Application Example (Contd…)

New Menu Itemcount = count + 1;ChildForm frmchild = new ChildForm(); ;frmchild.MdiParent = this;frmchild.Text = "Form " + count.ToString();frmchild.Show();

Cascade Menu Item this.LayoutMdi(MdiLayout.Cascade)

Horizontal Menu Itemthis.LayoutMdi(MdiLayout.TileHorizontal)

Vertical Menu Itemthis.LayoutMdi(MdiLayout.TileVertical)

(Source code: APPENDIX\MDIApplication\MDIApplication\MDIParent.cs)


Appendix: Advance Threads

• OverviewThread Safe classSingleton Pattern Thread Safe


Thread Safe class

• Thread safety is a computer Programming concept applicable in the context of multi threaded programs.

• To make the class as thread safe we have to mark all the member as static

Thread-safe programming is only necessary if you have data that can be modified by more than one thread at a time. In a client/server situation, usually the server has multiple clients. If all those clients can change shared data on the server, they must not be allowed to conflict with one another. Normally, if two clients try to change shared data, you have to hope that the first client is able to finish with the data before the second client begins to modify it. This situation is called racing.

A class is called thread safe when all the members of the class declared as synchronized.


Error Log Program

• Add the following namespaces in your programusing System.IO;using System.Threading;using System.Runtime.CompilerServices;

We will keep only one instance of the StreamWriter class which is going to be used by all the threads. So we will keep this instance as static.

class LogFile {static StreamWriter ErrorLog;

We will write LogStart() and Trace() method also as static.LogStart() method will open the file and Trace() method will

write the error message in the Error Log file.

(Source code: Appendix Thread\SynchronizedThreadEx\SynchronizedThreadEx\Logfile.cs)

Example:

You have created a multi threaded application. While executing the program if there is any error comes we want to register those errors in log file. Multiple thread is running this application, but on server you will have only one error log file where you have to register the error. So we will male this error log program as thread safe, where only one thread is allowed to write its error at a time. Other threads have to wait for the first thread to complete it task.


Error Log Program (Contd…)

[MethodImpl(MethodImplOptions.Synchronized)]public static void LogStart(string sFile) {

//open Trace Log fileErrorLog = new StreamWriter(File.Open(sFile, FileMode.Append, FileAccess.Write, FileShare.ReadWrite));

}



Error Log Program (Contd…)

[MethodImpl(MethodImplOptions.Synchronized )]public static void Trace() {

string str = Thread.CurrentThread.Name;Console.WriteLine(str + " - Writing error into log file \n");ErrorLog.WriteLine(str);ErrorLog.WriteLine("----------------------");for (int i = 0; i < 25; i++) {

ErrorLog.WriteLine(str + ",count : " + i);Console.WriteLine(str + ",count : " + i);

}ErrorLog.WriteLine("=============================");Console.WriteLine("------------------------------");Thread.Sleep(5000);ErrorLog.Flush();Console.WriteLine(str + " - Error writing into log file Complete......");Console.WriteLine("==============================");Console.WriteLine();

}



Test Programstatic void Main(string[] args) {

LogFile.LogStart("C:\\LOGFILE.txt");Thread t1 = new Thread(new ThreadStart(LogFile.Trace));Thread t2 = new Thread(new ThreadStart(LogFile.Trace));Thread t3 = new Thread(new ThreadStart(LogFile.Trace));Thread t4 = new Thread(new ThreadStart(LogFile.Trace));t1.Name = "Thread 1";t2.Name = "Thread 2";t3.Name = "Thread 3";t4.Name = "Thread 4";t1.Start();t2.Start();t3.Start();t4.Start();t1.Join();t2.Join();t3.Join();t4.Join();Console.WriteLine("\nMain Ends.............");Console.ReadLine();

}

(Source code: Appendix Thread\SynchronizedThreadEx\SynchronizedThreadEx\Program.cs)

Write a test program where we will create multiple thread and each thread will write some message to this log file.


Singleton Pattern using Thread safe

• a singleton is a class which only allows a single instance of itself to be created, and usually gives simple access to that instance.

Basic characteristics of the singleton class•A single constructor, which is private and parameter less•The class is sealed. This is optional, but may help the CLR to optimize•A static variable which holds a reference to the single created instance, if any.•A public static read only property means getting the reference to the single created instance.


Bad code which is not thread safe• Bad code which is not thread safe

public sealed class Singleton {static Singleton instance = null;Singleton(){ }public static Singleton Instance() {

if (instance == null) {Console.WriteLine("Creating instance...");System.Threading.Thread.Sleep(2000);instance = new Singleton();

}return instance;

}public static void RunThread() {

Instance();}

}

(Source code: Appendix Thread\SingletonThreadSafe\SingletonThreadSafe\Singleton.cs)


Testing Program

static void Main(string[] args) {Thread t1 = new Thread(new ThreadStart(Singleton.RunThread));Thread t2 = new Thread(new ThreadStart(Singleton.RunThread));Thread t3 = new Thread(new ThreadStart(Singleton.RunThread));Thread t4 = new Thread(new ThreadStart(Singleton.RunThread));t1.Start();t2.Start();t3.Start();t4.Start();t1.Join();t2.Join();t3.Join();t4.Join();

}

(Source code: Appendix Thread\SingletonThreadSafe\SingletonThreadSafe\Program.cs)

When you run this program, though it is a singleton program, it will create the multiple instance of the class.

Different threads could have evaluated the test if (instance==null) and found it to be true, then all thread created instances, which violates the singleton pattern.


Simple Thread Safe Singleton Pattern

public sealed class SingleTonSafeThread {static SingleTonSafeThread instance = null;SingleTonSafeThread(){ }[MethodImpl(MethodImplOptions.Synchronized)]private static SingleTonSafeThread Instance() {

if (instance == null) {Console.WriteLine("Creating instance...");System.Threading.Thread.Sleep(2000);instance = new SingleTonSafeThread();

}return instance;

}[public static void RunThread() {

Instance();}

}

(Source code: Appendix Thread\SingletonThreadSafe\SingletonThreadSafe\SingletonThreadSafe.cs)Mark the method as thread safe.


Test Program

static void Main(string[] args) {Thread t1 = new Thread(new ThreadStart(SingleTonSafeThread.RunThread));Thread t2 = new Thread(new ThreadStart(SingleTonSafeThread.RunThread));Thread t3 = new Thread(new ThreadStart(SingleTonSafeThread.RunThread));Thread t4 = new Thread(new ThreadStart(SingleTonSafeThread.RunThread));t1.Start();t2.Start();t3.Start();t4.Start();t1.Join();t2.Join();t3.Join();t4.Join();

}



Volatilepublic sealed class SingltonVolatile {

static volatile SingltonVolatile instance = null;static readonly object padlock = new object();SingltonVolatile() { }private static SingltonVolatile Instance() {

if (instance == null) {lock (padlock) {

if (instance == null) {Console.WriteLine("Creating instance...");instance = new SingltonVolatile();

}}

}return instance;

}public static void RunThread() {

Instance();}

}

(Source code: Appendix Thread\SingletonThreadSafe\SingletonThreadSafe\SingletonVolatile.cs)

The volatile keyword indicates that a field might be modified by multiple threads that are executing at the same time. Fields that are declared volatile are not subject to compiler optimizations that assume access by a single thread. This ensures that the most up-to-date value is present in the field at all times.The volatile keyword alerts the compiler that multiple threads will access the data member, and therefore it should not make any optimization assumptions about the state of this member.


Test Program

static void Main(string[] args) {Thread t1 = new Thread(new ThreadStart(SingltonVolatile.RunThread));Thread t2 = new Thread(new ThreadStart(SingltonVolatile.RunThread));Thread t3 = new Thread(new ThreadStart(SingltonVolatile.RunThread));Thread t4 = new Thread(new ThreadStart(SingltonVolatile.RunThread));t1.Start();2.Start();t3.Start();t4.Start();t1.Join();t2.Join();t3.Join();t4.Join();Console.WriteLine("Main end...");Console.ReadLine();

}



Thread PoolUsing System.Threading;

static void Main(string[] args) {int i, j;ThreadPool.GetMaxThreads(out i, out j);Console.WriteLine("Available Worker thread = " + i);Console.WriteLine("Available Asynchronus I/O thread = " + j);ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc));Thread.Sleep(1000);Console.WriteLine("Main thread exits.");Console.ReadLine();

}// This thread procedure performs the task.static void ThreadProc(Object stateInfo) {

Console.WriteLine("Hello from the thread pool.");}

(Source code: \Appendix Thread\ProjThreadPool\Class1.cs)

Many applications create threads that spend a great deal of time in the sleeping state, waiting for an event to occur. Other threads might enter a sleeping state only to be awakened periodically to poll for a change or update status information. Thread pooling enables you to use threads more efficiently by providing your application with a pool of worker threads that are managed by the system. One thread monitors the status of several wait operations queued to the thread pool. When a wait operation completes, a worker thread from the thread pool executes the corresponding callback function.The thread pool is created the first time you create an instance of the ThreadPool class. A thread pool is a collection of threads that can be used to perform a number of tasks in the background. This leaves the primary thread free to perform other tasks asynchronously.Once a thread in the pool completes its task, it is returned to a queue of waiting threads, where it can be reused. This reuse enables applications to avoid the cost of creating a new thread for each task.Where are ThreadPools used?On servers and in batch processing applications. ThreadPool has internal logic that makes getting a thread much less expensive. This is because the threads are already made and are just "hooked up" when required.

320


Appendix : Iterators

• OverviewIenumeratorIenumerable

321


IEnumerator Example

class IEnumeratorExample {string[ ] w_Days = { "Sun", "Mon", "Tue", "Wed", "Thr", "Fri", "Sat" };public System.Collections.IEnumerator GetEnumerator() {

for (int i = 0; i < w_Days.Length; i++) {yield return w_Days[i];

}}static void Main(string[ ] args) {

IEnumeratorExample Days = new IEnumeratorExample();// Iterate with the help of foreachforeach (string day in Days) {

System.Console.Write(day + " ");}Console.ReadLine();

}}

(Source code: Module09\IteratorExample\IteratorExample\IEnumeratorExample.cs)

When we use IEnumerator the name of the method is always GetEnumerator() and return type is IEnumerator.So, in a class we can have this method only once.

To overcome this limitation they have introduced IEnumerable

322


IEnumerable Example

class IEnumerableExample {public int[] numbers = new int[] {5,10,15,20};public string[] states = new string [] { "Maharashtra", "Gujarat", "Himachal" };public IEnumerable BuildintCollection() {

for (int i = 0; i < numbers.Length; i++) {yield return numbers[i];

}}public IEnumerable BuildStringCollection() {

for (int i = 0; i < states.Length; i++) {yield return states[i];

}}

(Source code: Module09\IteratorExample\IteratorExample\IEnumerableExample.cs)

An iterator is a method, get accessor or operator that enables foreach iteration in a class or structure.

Iterator traverse the data structure in the class.

You can have multiple IEnumerable methods because you can give your own name to this method. Each method must have a unique name and can be invoked in client code by foreach statement

The return type of an iterator must be IEnumerable, IEnumerator, IEnumerable<T>, or IEnumerator<T>.

The yield keyword is used to specify the return value. When the yield return statement is reached, the current location is stored. Execution is restarted from this location the next time the iterator is called.

323


IEnumerable Example (Contd…)

static void Main() {IEnumerableExample obj = new IEnumerableExample();

// Display the collection items:System.Console.WriteLine("Values in the int collection are:");

foreach (int i in obj.BuildintCollection()) {System.Console.Write(i + "\t");

}Console.WriteLine("\n----------------------\n");

System.Console.WriteLine("Values in the string collection are:");foreach (string st in obj.BuildStringCollection()) {

Console.Write (st +"\t");}Console.ReadLine();

}}

(Source code: Module09\IteratorExample\IteratorExample\IEnumerableExample.cs)


Appendix: Reflection

• OverviewReflection mechanismObtaining the content of assembly at run time

324

325


Reflection features

• Reflection is ability to find out the information about the objects at run-time.

• Using reflection we can read types from assembly, create instances of types dynamically, invoke methods, etc.

• Add System.Reflection Namespace

Every managed application in .NET is deployed as an assembly and every assembly defines certain types (like class, interface, structure, enum, delegate).

These types are revealed in the form of metadata.

Metadata gives a detailed description of types and external assemblies that are used by the types.

Reflection allows us to access data from assembly

The System.Reflection namespace contains classes to read an assembly.


Hierarchical Representation of Metadata Information

Assembly

Module(s)

Constructor(s) Method(s)

Parameter(s)

Field(s) Property(s)

Type(s)class(s), interface(s), structure(S), enum(s)

delegate(s)

Parameter(s)

326

327


Reflection Codeclass Shape {

int l, b;public Shape() {

l = 5;b = 3;Console.WriteLine("inside constructor");Console.WriteLine("--------------------");

}public void Display() {

Console.WriteLine("Inside Display Method");Console.WriteLine("l = " + l);Console.WriteLine("b = " + b);Console.WriteLine("----------------------");

}public int RectangleArea() {

return l * b;}public static float CircleArea(int r) {

return 3.14f * r * r;}

}

(Source code: Appendix Reflection\Reflection\Reflection\Shape.cs)

328


Reflection Code (Contd…)

static void Main(string[ ] args) {Object obj;try {

//load assemblyAssembly assembly = Assembly.LoadFrom("Reflection.exe");

//search for the typeType[] types = assembly.GetTypes();Console.WriteLine("The types contained within the assembly are : ");foreach (Type type in types){

Console.WriteLine("\tType name: " + type.Name);}Console.WriteLine("--------------------");

//load the type//assembly.GetType(string name,bool throwonerror, bool ignorecase )Type ClassType = assembly.GetType("Reflection.Shape", true, true);

(Source code: Appendix Reflection\Reflection\Reflection\Program.cs)

329



if (ClassType == null)Console.WriteLine(ClassType.Name + " type does not exist");

elseConsole.WriteLine(ClassType.Name + " type exist");

Console.WriteLine("--------------------");

//create the instance of the typeobj = Activator.CreateInstance(ClassType);

//method invokingMethodInfo methodinfo = ClassType.GetMethod("Display");if (methodinfo.IsStatic == true)//invoke method//object on which to invoke the method (if method is static then null)//method parameter if no parameter then null

methodinfo.Invoke(null, null);else if (methodinfo.IsStatic == false)

methodinfo.Invoke(obj, null);


330



//method with return valueMethodInfo methodinfo1 = ClassType.GetMethod("RectangleArea");if (methodinfo1.IsStatic == true)

Console.WriteLine("Area of Rectangle = " + methodinfo1.Invoke(null, null).ToString());

else if (methodinfo1.IsStatic == false){

Console.WriteLine("Area of Rectangle = " + methodinfo1.Invoke(obj, null).ToString());

}Console.WriteLine("--------------------");


331



//method with parameterint r = 10;Object[] param = new Object[1];param[0] = r;MethodInfo methodinfo2 = ClassType.GetMethod("CircleArea");if (methodinfo2.IsStatic == true)

Console.WriteLine("Area of Circle = " + methodinfo2.Invoke(null, param).ToString());

else if (methodinfo2.IsStatic == false)Console.WriteLine("Area of Circle = " + methodinfo2.Invoke(obj,

param).ToString());}catch (Exception ex){

Console.WriteLine(ex.Message);}Console.ReadLine();

}



Appendix: Serialization

• OverviewWhat is serializationTypes of serialization

• Binary• SOAP• XML


Serialization

• Serialization allows programs to persist or transfer the state of an object into a stream (file, memory, network etc.)

• .Net offers Binary, SOAP and XML Serialization

Object Serialization is a process through which an object's state is transformed into some serial data format, such as XML or a binary format.Binary is more efficient (time and memory used)Binary is completely human unreadable. SOAP isn’t much better.XML does not serialize private class members

Mark the class wth [Serializable] attribute. For non serializing the member mark with the attribute [NonSerialized] or in case of XML Serialization mark with the attribute [XmlIgnore].


Class Person[Serializable]class Person {

private string strname;private DateTime dtbirthdate;[NonSerialized]private int intAge;

public string Name {get { return strname; }set { strname = value; }

}

public DateTime Birthdate {get { return dtbirthdate; }set { dtbirthdate = value; }

}

(Source code: Appendix Serialization\Serialization\Serialization\02BinarySerialization.cs\Person.cs)


Class Person (Contd…)

public Person(string name, DateTime birthdate) {this.strname = name;this.dtbirthdate = birthdate;

}

public int Age {get {

if (intAge == 0) {intAge = System.DateTime.Now.Year - Birthdate.Year;if (Birthdate.DayOfYear > System.DateTime.Now.DayOfYear) {

intAge -= 1;}

}return intAge;

}}

}

(Source code: Appendix Serialization\Serialization\Serialization\02BinarySerialization.cs\Person.cs)


Binary Serialization

Binary Formatter class is available in the namespace

System.Runtime.Serialization.Formatters.Binary

(Source code: Appendix Serialization\Serialization\Serialization\02BinarySerialization.cs)


Binary Serialization Write Object

• Add the namespaceusing System.Runtime.Serialization.Formatters.Binary;using System.IO;

Person p = new Person("Bhavana", Convert.ToDateTime("01/01/2001"));FileStream stream = new FileStream("c:\\Person.txt", FileMode.Create );BinaryFormatter formatter = new BinaryFormatter();formatter.Serialize(stream, p);stream.Close();richTextBox1.Text = "Data saved in a file";



Binary Serialization Read Object

richTextBox1.Clear();FileStream stream = new FileStream("c:\\Person.txt", FileMode.Open);BinaryFormatter formatter = new BinaryFormatter();Person p =(Person) formatter.Deserialize(stream);stream.Close();richTextBox1.AppendText("Name = " + p.Name + "\nAge = " + p.Age);richTextBox1.AppendText("\nBirthdate = " + p.Birthdate);



Read & Write Multiple Object

List<Person> personlist = new List<Person>();personlist.Add(new Person("Bhavana", Convert.ToDateTime("01/01/2001")));personlist.Add(new Person("Shraddha", Convert.ToDateTime("01/01/2002")));personlist.Add(new Person("Vishal", Convert.ToDateTime("01/01/2003")));FileStream stream = new FileStream("C:\\Persons.txt", FileMode.Create);BinaryFormatter formatter = new BinaryFormatter();formatter.Serialize(stream, personlist);stream.Close();FileStream stream1 = new FileStream("C:\\Persons.txt", FileMode.Open);List<Person> TotalPersons = (List<Person>)formatter.Deserialize(stream1);stream1.Close();foreach (Person p in TotalPersons) {

richTextBox1.AppendText(p.Name + " " + p.Birthdate + " " + p.Age.ToString() + "\n");}



SOAP Serialization

Add reference for the namespace

System.Runtime.Serialization.Formatters.Soap

(Source code: Appendix Serialization\Serialization\Serialization\03SOAPSerialization.cs)


SOAP Serialization Write Object

Person p = new Person("Bhavana", Convert.ToDateTime("01/01/2001"));FileStream stream = new FileStream("c:\\PersonSoap.XML", FileMode.Create);SoapFormatter formatter = new SoapFormatter();formatter.Serialize(stream, p);stream.Close();richTextBox1.Text = "Data saved in a file";



SOAP Serialization Read Object

richTextBox1.Clear();FileStream stream = new FileStream("c:\\PersonSoap.XML", FileMode.Open);SoapFormatter formatter = new SoapFormatter();Person p = (Person)formatter.Deserialize(stream);stream.Close();richTextBox1.AppendText("Name = " + p.Name + "\nAge = " + p.Age);richTextBox1.AppendText("\nBirthdate = " + p.Birthdate);richTextBox1.AppendText("\nBirthdate day of the year = " +

p.Birthdate.DayOfYear.ToString());richTextBox1.AppendText("\nCurrent day of the year = " +

DateTime.Now.DayOfYear.ToString());



XML Serialization

• Rules for creating class for XML SerializationXML serialization serializes only the public fields and property values of an object into an XML stream. XML serialization does not include type information. XML serialization serialize only the public type.XML serialization requires a default constructor to be declared in the class that is to be serialized. XML serialization requires all properties that are to be serialized as read write properties. Read only properties are not serialized.

XML was designed to be a technology for data exchange across heterogeneous systems. It can be easily transmitted between distributed components because of its platform independence and its simple, text-based, self-describing format.


Employee Class

• Add the following namespace using System.Xml.Serialization;using System.Collections;

public class Emp {[XmlAttribute("empNo")]public int empNo;[XmlElement("name")]public string name;//[XmlElement("address")][XmlIgnore]public string address;[XmlElement("salary")]public double salary;

(Source code: Appendix Serialization\Serialization\Serialization\Employee.cs)


Employee Class (Contd…)

public Emp(){ }public Emp(int empNo,string name, string address, double sal) {

this.empNo = empNo;this.name = name;this.address = address;this.salary = sal;

}public double AnnualSalary() {

return salary * 12;}

}




[XmlRoot("employeeList")]public class Employee {

private ArrayList listEmployee;

public Employee() {listEmployee = new ArrayList();

}

public int AddEmp(Emp emp) {return listEmployee.Add(emp);

}




[XmlElement("emp")]public Emp[] Emps {

get {Emp[] emps = new Emp[listEmployee.Count];listEmployee.CopyTo(emps);return emps;

}Set {

if (value == null) return;Emp[] emps = (Emp[])value;listEmployee.Clear();foreach (Emp emp in emps)

listEmployee.Add(emp);}

}}



Employee XML Serialization

using System.IO;using System.Xml.Serialization;



XML Serialization Write Object

Employee empList = new Employee();empList.AddEmp(new Emp(1,"Bhavana", "Mumbai", 8000.00));empList.AddEmp(new Emp(2,"Shraddha", "Pune", 7000.00));empList.AddEmp(new Emp(3,"Vishal", "Delhi", 9000.00));//serializationXmlSerializer serializer = new XmlSerializer(typeof(Employee));StreamWriter writer = new StreamWriter("C:\\emp.xml");serializer.Serialize(writer, empList);writer.Close();

(Source code: Appendix Serialization\Serialization\Serialization\04EmployeeXMLSerialization.cs)


XML Serialization Read Object

richTextBox1.Clear();Employee newList;XmlSerializer serializer = new XmlSerializer(typeof(Employee));StreamReader reader = new StreamReader("C:\\emp.xml");newList = (Employee) serializer.Deserialize(reader);reader.Close();int empcount = newList.Emps.Count();richTextBox1.AppendText("total No of Employees = " + empcount.ToString() + "\n");for (int i = 0; i < empcount; i++) {

richTextBox1.AppendText(newList.Emps[i].empNo.ToString() +" " + newList.Emps[i].name + " " + newList.Emps[i].address + " " + newList.Emps[i].salary.ToString() +" " + newList.Emps[i].AnnualSalary().ToString() + "\n");

}

(Source code: Appendix Serialization\Serialization\Serialization\04EmployeeXMLSerialization.cs)

351


Appendix:SQL Bulk Copy


SqlConnection conn = new SqlConnection(connstr);conn.Open();SqlCommand cmdcreatetable = new SqlCommand("create table Productnew1 (prodid

int, prodname varchar(40))", conn);cmdcreatetable.ExecuteNonQuery();conn.Close();

(Source code: Module12\DatabaseApplication\DatabaseApplication\12SQLBulkCopy.cs)

352


SQL Bulk Copy (Contd…)

SqlConnection Sourceconn = new SqlConnection(connstr);Sourceconn.Open();SqlCommand cmd = new SqlCommand("select productid, productname from

products where productid > 70 and Productid <78", Sourceconn);SqlDataReader reader = cmd.ExecuteReader();SqlConnection destConn = new SqlConnection(connstr);destConn.Open();SqlBulkCopy bcp = new SqlBulkCopy(destConn);bcp.DestinationTableName = "ProductNew1";//bcp.ColumnMappings.Add(0, 0)//bcp.ColumnMappings.Add(1, 1)bcp.ColumnMappings.Add("productid", "prodid");bcp.ColumnMappings.Add("productname", "prodname");bcp.WriteToServer(reader);destConn.Close();reader.Close();Sourceconn.Close();MessageBox.Show("Record copied");

(Source code: Module12\DatabaseApplication\DatabaseApplication\12SQLBulkCopy.cs)

353


Appendix : Batch Update

• Write the code in Batch Update Button Click Event

string connstr = ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;SqlConnection conn = new SqlConnection(connstr);SqlDataAdapter adp = new SqlDataAdapter("select * from productnew", conn);DataSet ds = new DataSet();adp.Fill(ds);Console.WriteLine(ds.Tables.Count.ToString());adp.RowUpdating += new SqlRowUpdatingEventHandler(adprowupdating);adp.RowUpdated += new SqlRowUpdatedEventHandler(adprowupdated);foreach (DataRow dr in ds.Tables[0].Rows) {

string name = dr["prodname"].ToString();dr["prodname"] = name;

}

(Source code: Module12\DatabaseApplication\DatabaseApplication\13BatchUpdate.cs)

354


Batch Update (Contd…)

adp.UpdateCommand = new SqlCommand("update productnew set prodname='xxx' where prodid>70", conn);adp.UpdateCommand.UpdatedRowSource = UpdateRowSource.None;adp.UpdateBatchSize = 2;adp.Update(ds);label1.Text = "Row updated = " + x;label2.Text = "Rwo updating = " + y;

private void adprowupdated(object sender, EventArgs e){

x++;}

private void adprowupdating(object sender, EventArgs e){

y++;}

(Source code: Module12\DatabaseApplication\DatabaseApplication\13BatchUpdate.cs)

355


Appendix : Multiple Active Result Set

(Source code: Module12\DatabaseApplication\DatabaseApplication\14MARS.cs)

356


Multiple Active Result Set (Contd…)

//By default, MARS is disabled when connecting to a MARS-enabled host such as SQL Server 2005. It must be enabled in the connection string.

int categoryid;SqlDataReader productReader = null;string categorysql = "select categoryid, categoryname from categories";string productsql = "select productid, productname from products where

categoryid=@catid";using (SqlConnection Connection = new SqlConnection("Data Source = .\\sa1;

Integrated Security=true;Initial Catalog= Northwind;MultipleActiveResultSets=True“ )){

SqlCommand categoryCmd = new SqlCommand(categorysql, Connection);SqlCommand productCmd = new SqlCommand(productsql, Connection);productCmd.Parameters.Add("@catid", SqlDbType.Int);Connection.Open();


357


Multiple Active Result Set (Contd…)

using (SqlDataReader categoryReader = categoryCmd.ExecuteReader()) {while (categoryReader.Read()) {

lstmars.Items.Add (categoryReader["categoryname"].ToString());categoryid = (int)categoryReader["categoryid"];productCmd.Parameters["@catid"].Value = categoryid;// The following line of code requires a MARS-enabled connection.productReader = productCmd.ExecuteReader();using (productReader) {

while (productReader.Read()) {lstmars.Items.Add (" " + productReader[“productName”].ToString());

}}

}Connection.Close();

}}

}


358


Appendix : Reading and Writing Data to XML

DataSet ds;

• Form Load Eventstring connstr =

ConfigurationManager.ConnectionStrings["NorthwindConnStr"].ConnectionString;SqlConnection conn = new SqlConnection(connstr);string sql = "select categoryid, categoryname from categories order by categoryid";SqlDataAdapter adp = new SqlDataAdapter(sql, conn);ds = new DataSet();adp.Fill(ds);

(Source code: Module12\DatabaseApplication\DatabaseApplication\15XML.cs)

359


Reading and Writing Data to XML (Contd…)

• WriteXML Button

if (!File.Exists("C:\\category.xml")) {ds.WriteXml("c:\\category.xml");

}btnreadxml.Visible = true;

• ReadXML Button

ds.Clear();ds.ReadXml("C:\\category.xml");dataGridView1.DataSource = ds.Tables[0];

(Source code: Module12\DatabaseApplication\DatabaseApplication\15XML.cs)

360


Appendix : Data Independent Provider

(Source code: Module12\DatabaseApplication\DatabaseApplication\16ProviderFactories.cs)

361


Data Independent Provider (Contd…)

• Add the following namespace• using System.Data.Common;• Form Load Event

DataTable table = DbProviderFactories.GetFactoryClasses();lstprovider.DisplayMember = table.Columns["InvariantName"].ToString();lstprovider.ValueMember = table.Columns["InvariantName"].ToString();lstprovider.DataSource = table;


362



• ListBox SelectedIndexChange Eventstring provider = lstprovider.SelectedValue.ToString();if (provider == "System.Data.SqlClient") {

DbProviderFactory factory = DbProviderFactories.GetFactory(provider );using (DbConnection conn = factory.CreateConnection()) {conn.ConnectionString = "data source=.\\sa1; initial catalog=northwind; integrated

security=true";conn.Open();DbCommand cmd = factory.CreateCommand();cmd.CommandText = "select * from customers";cmd.Connection = conn;DbDataReader reader = cmd.ExecuteReader();DataTable custtable = new DataTable();custtable.Load(reader);conn.Close();dataGridView1.DataSource = custtable;}

}


363



else if (provider == "System.Data.OleDb") {DbProviderFactory factory = DbProviderFactories.GetFactory(provider );using (DbConnection conn = factory.CreateConnection()) {conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;data

source=c:\\northwind.mdb;";conn.Open();DbCommand cmd = factory.CreateCommand();cmd.CommandText = "select * from Categories";cmd.Connection = conn;DbDataReader reader = cmd.ExecuteReader();DataTable categorytable = new DataTable();categorytable.Load(reader);conn.Close();dataGridView1.DataSource = categorytable;}

}



Appendix : TreeView Example with Database

(Source code: Module12\DatabaseApplication\DatabaseApplication\17TreeViewExample.cs)


TreeView Example with Database Code

• Class level declaration

SqlConnection conn;SqlDataAdapter adp;DataSet ds = new DataSet();



• Form Load Event

conn = new SqlConnection("server=.\\sa1;database=northwind;integratedsecurity=true");

adp = new SqlDataAdapter("select table_name from information_schema.tableswhere table_type='Base Table' order by table_name", conn);

adp.Fill(ds);treeView1.Nodes.Add("Northwind");int rows = ds.Tables[0].Rows.Count;for (int i = 0; i <= rows - 1; i++) {

treeView1.Nodes[0].Nodes.Add(ds.Tables[0].Rows[i][0].ToString());}for (int i = 0; i <= rows - 1; i++) {

treeView1.Nodes[0].Nodes[i].Nodes.Add("column");treeView1.Nodes[0].Nodes[i].Nodes.Add("data");

}



ds = new DataSet();if (e.Node.Text == "column") {

string str = e.Node.Parent.Text;adp = new SqlDataAdapter("selectCOLUMN_NAME,DATA_TYPE,CHARACTER_MAXIMUM_LENGTH from northwind.information_schema.columns where table_name = '" + str + "'", conn);

adp.Fill(ds);dataGridView1.DataSource = ds.Tables[0];

}else if (e.Node.Text == "data") {

string str = e.Node.Parent.Text;adp = new SqlDataAdapter("select * from [" + str + "]", conn);adp.Fill(ds);dataGridView1.DataSource = ds.Tables[0];

}Else {

dataGridView1.DataSource = null;}

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