Dip. C Sharp Dot Net

7/31/2019 Dip. C Sharp Dot Net

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Diploma Course in Programming with C#.Net

Conducted by LAVTC Ratmalana(Prepared by Suranga Fernando) 1

.Net Architecture

CONTENTS

What is .NET Framework?o CLR, IL & multiplatformo Multi-language supporto Common API

Enterprise Applications

o J2EE specs and Application Serverso .NET - Windows OS + .NET Servers

Tools to develop (IDE)

o Visual Studio.NET

o Compare with Java (Netbeans, Eclipse, etc.)

WHAT IS .NETFRAMEWORK?

What is .NET Framework?

Everything needed to build and deploy .NET Applications

Everything - Runtime environment, Classes, APIs, Tools, etc.

The .NET Framework is required to build and run any .NET application and is availabletoday as a download via Windows Update or directly from the Microsoft .NET Web site

(http://www.microsoft.com/net).

A major and important component of .NET Framework is the runtimeenvironment

What is a runtime environment?o This is what an application sees!

What is an application?o Application is synonymous to Program = set of instructions to do something

Runtime environmentunderstands the instructions and executes them

CLR

The runtime environment in .NET Framework is called the Common Language Runtime(CLR)

A .NET Application is compiled intoIntermediate Language (IL), also known asMicrosoftIntermediate Language (MSIL) or managed code.

CLR compiles IL code and executes it.


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.NET applications compile to Intermediate Language

CLR compiles IL code to native code (JIT compilation) at runtime

WHY NOT USE OSS RUNTIME?

Operating System (OS) provides a runtime environment.o Not standard across different OSs.

Portability!!!o Compile once, run anywhere.

MICROSOFTS STRATEGY

!

!

" " " "

#$!%#'

#

!

("("


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.NET LANGUAGES

Multiple languages (syntaxes) are supported in .NET Framework to build .NETApplications.

E.g. C#.Net, Visual Basic.Net, ASP.Net etc.

Different language compilers generate IL code.

.NET supports multiple languages.

ASSEMBLY

In .NET, applications (multiple classes etc.) are compiled into a single assembly (usuallytaking the form of EXE or DLL).

Every assembly contains metadata that describes it, dependencies on other assemblies, andversion information

Assemblies have the ability to make cross-references to other assemblies with informationstored in metadata

API

In .NET Framework provides a comprehensive a standard class library, called .NETFramework Class Library, which assist to develop .NET applications in any .NET

language.

.NET Assembly inIL

C#Compiler

VBCompiler

C++Compiler

VJ#Compiler

C# App VB App C++ App VJ# App

CLR


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ENTERPRISE APPLICATIONS

Enterprise Applications require a lot of features including:

security,

messaging,

transactions,

logging and etc.

ENTERPRISE APPLICATIONS:.NET APPROACH

No Application Server.

Services/features distributed across various parts of the Operating System.

.NET Framework APIs and services provide many features/services.

In addition to OS, a range of products are available aimed for the enterprise:

Application Center

BizTalk Server Commerce Server

Content Management Server

Exchange Server

Host Integration Server

SharePoint Portal Server

SQL Server and etc

DEPLOYING .NET APPLICATIONS

Three alternatives exist for deploying a .NET Application:

Run as a Windows ServiceWindows Services are system-level processes that run on the machine independent of

the user who is logged in. Typical services include functions of the operating system,

schedulers, virus scanners, database engines, and network components. Using templates

supplied with Visual Studio .NET, it is possible to take a .NET assembly and run it as a

service.

Host through IIS

One way of hosting an assembly is to take advantage of IIS features. IIS allows anassembly to be deployed and will handle incoming connections, protocols, pooling, and

security via a configuration file located with the assembly.

Use Component ServicesComponent Services also known as COM+ Services, enable you to include

functionalities such as recycling, state, transactions, method-level security, logging,

impersonation, for hosted components through either an administration tool or the use

of attributes.


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TOOLS

IDEs play a key role for developer productivity in either platform.

In .NET, Visual Studio.NET is the predominately used IDE.

In Java, a range of tools exists from different vendors: Eclipse, NetBeans, Sun ONEStudio, etc.

SUMMARY

.NET framework

CLR

.NET has multi-language support.

.NET technology and products from a single vendor: Microsoft

CLR Common Language Runtime.

API Application Programming Interface.

JIT Just in Time.


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About C # .Net

.NET FRAMEWORK

The Microsoft .NET Framework is a software framework that can be installed oncomputers running Microsoft Windows operating systems. It includes a large library of coded

solutions to common programming problems and a virtual machine that manages the execution of

programs written specifically for the framework. The .NET Framework is a Microsoft offering and

is intended to be used by most new applications created for the Windows platform.

ABOUT CSHARP

C# (pronounced "C Sharp") is a multi-paradigm programming language encompassingimperative, functional, generic, object-oriented (class-based), and component-oriented

programming disciplines. It was developed by Microsoft within the .NET initiative and later approved as a standard

by Ecma (ECMA-334) and ISO (ISO/IEC 23270).

C# is one of the programming languages designed for the Common LanguageInfrastructure.

C# is intended to be a simple, modern, general-purpose, object-oriented programminglanguage.

Its development team is led by Anders Hejlsberg, the designer of Borland's Turbo Pascal.

It has an object-oriented syntax based on C++.

It was initially named Cool, which stood for "C-like Object Oriented Language".

However, in July 2000, when Microsoft made the project public, the name of theprogramming language was given as C#.

The most recent version of the language is 3.0 which were released in conjunction with the.NET Framework 3.5 in 2007. The next proposed version, 4.0, is in development.

C# is the programming language that most directly reflects the underlying CommonLanguage Infrastructure (CLI).

Most of its intrinsic types correspond to value-types implemented by the CLI framework.

However, the language specification does not state the code generation requirements of thecompiler: that is, it does not state that a C# compiler must target a Common Language

Runtime, or generate Common Intermediate Language (CIL), or generate any other specific

format.

Theoretically, a C# compiler could generate machine code like traditional compilers of C++or FORTRAN. In practice, all existing compiler implementations target CIL.


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C# VERSIONS

1. C# 2.02. C# 3.03. C# 4.0

FEATURES

There are no global variables or functions.

C# supports a strict Boolean data type, bool.

Managed memory cannot be explicitly freed.

Multiple inheritances are not supported etc


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Introduction to Programming Environments

INTRODUCTION

What is a Computer? Up until the late 1940s, a Computer was a person who performed calculations.

What about now?

Programs

Programs are sequence of step by step instructions to the computer

Programs, and the data values processed by programs, are called software.

PROGRAMMING LANGUAGES

1. Low-Level Programming Languages Machine language:

Used by early computers

Executable by machines, almost incomprehensible to humans.

Programming in machine language is very tedious and prone to errors

Ex:

11001010000100101000010101110100

11000101010001110010101000110010

Assembly language:Mnemonics used for instruction codes and memory locations.

Not directly understandable by machine. They must be translated. Easier for humans to use and still in use today.

Ex:

ADD X, Y, Reg1

ADD Reg1, Z, Reg2

STORE Reg2 SUM

2. High-Level Programming Languages:

Instructions look more like English and Math.

Generally result in multiple low level commands, for a single high level statement. Uses syntax resembling combination of mathematical notation and English.

Easy for humans to understand.

Not understandable by machines, must be translated using a compiler or aninterpreter.

Programming tools such as Integrated, Programming Environment (IDE) with adebugger is available to aid in programming process.


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PROGRAMMING LANGUAGE TRANSLATION

1. Assemblers:

Translate statement from assembly language to machine language.

Generally use table look-up techniques.

2. Interpreters:

Translate and execute each high-level statement, one at a time.

3. Compilers

Translate the entire high level language program, called the source code, to machinelanguage and store the result.

Machine language code produced by compilers is called object code.


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Data Types

WHAT ARE DATA TYPES?

A data type is an attribute of a data which tells the computer (and the programmer)

something about the kind of data it is.

VARIABLE DEFINITION

A variable is a named memory location that can be assigned a value. To declare a variable,

you will use a statement like this:

type var-name;

Type specifies the type of variable being declared.

var-name is the name of the variable.

DEFINE AND ASSIGN VALUE TO VARIABLES.

The general form of initialization is shown here:

using System;

classMainClass

{

publicstaticvoid Main()

{

int x; // declares a variableint y; // declares another variable

x = 100; // this assigns 100 to x

Console.WriteLine("x contains " + x);

y = x / 2;

Console.Write("y contains x / 2: ");

Console.WriteLine(y);

}

}

DYNAMIC INITIALIZATION

Declare two or more variables using the same declaration statement. Just separate their

names by commas:

int x, y; // both declared using one statement


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THE C#VALUE TYPES

C# contains two general categories of built-in data types:

Value types:

Type meaning Bool represents true/false values, byte 8-bit unsigned integer, charCharacter, decimal Numeric type for financial calculations double Double-precision

floating point float Single-precision floating point int Integer long Long integer sbyte 8-

bit signed integer short short integer uint An unsigned integer ulong An unsigned long

integer ushort An unsigned short integer.

Reference types:

C#'s reference types are defined by classes.


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CONVERTING NUMERIC STRINGS TO THEIR INTERNAL REPRESENTATION LITERALS

For the numeric types, the .NET structure names and their C# keyword equivalents are

shown here:

.NET Structure Name C# Name

Decimal decimal

Double double

Single float

Int16 short

Int32 int

Int64 long

UInt16 ushort

UInt32 uint

UInt64 ulongByte byte

Sbyte sbyte

The structures are defined inside the System namespace. The fully qualified name for Int32

is System.Int32.

LITERALS

Literals refer to fixed values that are represented in their human-readable form. To specify a long literal, append an l or an L. For example, 12 is an int, but 12L is a long.

To specify an unsigned integer value, append a u or U. Thus, 100 is an int, but 100U is a uint.

To specify an unsigned, long integer, use ul or UL. For example, 984375UL is of type ulong.

To specify a float literal, append an F or f to the constant. For example, 10.19F is of type float.

To specify a decimal literal, follow its value with an m or M. For example, 9.95M is a decimalliteral.

A hexadecimal literal must begin with 0x (a zero followed by an x).


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FAMILY OF INTEGERS

C# defines nine integer types:

char, byte, sbyte, short, ushort, int, uint, long and ulong.

char type is used for representing characters.

The integer structures are:

Byte, SByte, Int16, UInt16, Int32, UInt32, Int64, UInt64.

The integer structures also define the following const fields:

MaxValue

MinValue

METHODS SUPPORTED BY THE INTEGER STRUCTURES

Method Meaning

public int CompareTo(object v)

Returns 0 if the values are equal. Returns a

negative value if the invoking object has a lower

value. Returns a positive value if the invoking

object has a greater value.

public override bool Equals(object v) Returns true if equal.

public override int GetHashCode() Returns the hash code.

public TypeCode GetTypeCode() Returns the TypeCode enumeration value. Forexample, for Int32, the type code is

TypeCode.Int32.

public static retType Parse(string str) Parses the string.

public static retType Parse(string

str,IFormatProvider fmtpvdr)

Parse string using the culture-specific information

provided by fmtpvdr.

public static retType Parse(string str,

NumberStyles styles)

Parse string using the style information provided

by styles.

public static retType Parse(string str,

NumberStyles styles,IFormatProvider fmtpvdr)

Parse string using the style information provided

by styles and the culture-specific format

information provided by fmtpvdr.public override string ToString() Convert value to string.

public string ToString(string format)Convert value to string as specified by the format

string.

public stringToString(IFormatProvider fmtpvdr)

Returns the string representation of the value of

the invoking object using the culture-specific

information.

public stringToString(string

format,IFormatProvider fmtpvdr)

Returns the string representation of the value of

the invoking object using the culture-specific

information and the format.


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NAMESPACE

The namespace provides a way to keep one set of names separate from another.

Names declared in one namespace will not conflict with the same names declared inanother.

The namespace System is reserved for items in the .NET Framework class library.

The using keyword simply states that the program is using the names in the givennamespace.

NAMESPACE WITH CLASS DEFINITION

using System;

namespace HelloWorld

{

//

//Summary description for Class1.

//

classClass1

{

//

//The main entry point for the application.

//

//[STAThread]

staticvoid Main(string[] args)

{

System.Console.WriteLine( "Hello world from C#" );

}

}}

PARSING STRINGS TO CREATE DATA TYPES

Structure Conversion Method

Decimal static decimal Parse(string str)

Double static double Parse(string str)

Single static float Parse(string str)

Int64 static long Parse(string str)

Int32 static int Parse(string str)

Int16 static short Parse(string str)

UInt64 static ulong Parse(string str)

UInt32 static uint Parse(string str)

UInt16 static ushort Parse(string str)

Byte static byte Parse(string str)

SByte static sbyte Parse(string str)


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Example-01: bool

using System;

classMainClass

{

publicstaticvoid Main(string[] args)

{

bool myBool = bool.Parse("True");

Console.WriteLine("-> Value of myBool: {0}", myBool);

}

}

Example-02: int

using System;

classMainClass

{


{

int myInt = int.Parse("8");Console.WriteLine("-> Value of myInt: {0}", myInt);

}

}

Example-03: char

using System;

classMainClass

{


{

char myChar = char.Parse("w");

Console.WriteLine("-> Value of myChar: {0}\n", myChar);

}

}

THE BOOL TYPE

The bool type represents true/false values.

C# defines the values true and false using the reserved words 'true' and 'false'.

A variable or expression of type bool will be one of these two values.

There is no conversion defined between bool and integer values.

OUTPUT A BOOLEAN VARIABLE WITH CONSOLE.WRITELINE

using System;

classExample

{


{

Console.WriteLine("10 > 9 is " + (10 > 9));

}

}


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Operators

THE ASSIGNMENT OPERATOR

It has this general form:var = expression;

The general form of the shorthand is

var op = expression;

Thus, the arithmetic and logical assignment operators are:

+=

-=

*=

/=%=

&=

|=

^=

ARITHMETIC OPERATORS

Operator Meaning

+ Addition

- Subtraction (also unary minus)

* Multiplication

/ Division

% Modulus

++ Increment

-- Decrement


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//When / is applied to an integer, any remainder will be truncated.

//For example, 10/3 will equal 3 in integer division.

using System;

classMainClass

{

staticvoid Main(string[] args)

{

int a,b,c,d,e,f;

a = 1;

b = a + 6;

Console.WriteLine(b);

c = b - 3;

Console.WriteLine(c);

d = c * 2;

Console.WriteLine(d);

e = d / 2;

Console.WriteLine(e);

f = e % 2;

Console.WriteLine(f);

}

}

INCREMENT AND DECREMENT (PREFIX &POSTFIX)

The ++ and the -- are the increment and decrement operators.

The increment operator adds 1 to its operand, and the decrement operator subtracts 1.

x = x + 1;

can be written as

++x; // prefix form

or as

x++; // postfix form

RELATIONAL OPERATORS

Operator Meaning

== Equal to

!= Not equal to

> Greater than

< Less than

>= Greater than or equal to


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Arrays

WHAT IS AN ARRAY?

An array is a collection of variables of the same type that are referred to by a commonname.

To declare a one-dimensional array, you will use this general form:

type[] array-name = new type[size];

Array Declaration with initialization, the general form for initializing a one-dimensionalarray is shown here:

type[] array-name = { val1, val2, val3, ..., valN };

ARRAY OVERVIEW

An array can be Single-Dimensional, Multidimensional or Jagged.

The default value of numeric array elements are set to zero, and reference elements are setto null.

A jagged array is an array of arrays, therefore its elements and reference types areinitialized to null.

Arrays are zero indexed: an array with n elements is indexed from 0 to n-1.

Array elements can be of any type, including an array type.

Array types and reference types derived from the abstract base type Array. Since this type

implements IEnumerable and IEnumerable), you can use foreach iteration onall arrays in C#.

1. SINGLE DIMENSIONAL ARRAYS

Declare an array of five integers as in the following example:int[] array = newint[5];

This array contains the elements from array[0] to array[4]. The new operator is usedto create the array and initialize the array elements to their default values. In this

example, all the array elements are initialized to zero.

An array that stores string elements can be declared in the same way. For example:string[] stringArray = newstring[6];


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SINGLE DIMENSIONAL ARRAY INITIALIZATION

It is possible to initialize an array upon declaration, in which case, the rank specifier isnot needed because it is already supplied by the number of elements in the

initialization list. For example:

int[] array1 = newint[] { 1, 3, 5, 7, 9 };

A string array can be initialized in the same way. The following is a declaration of astring array where each array element is initialized by a name of a day:

string[] weekDays = new string[] {"Sun","Mon","Tue","Wed","Thu",

"Fri","Sat"};

When you initialize an array upon declaration, you can use the following shortcuts:

int[] array2 = { 1, 3, 5, 7, 9 };

string[] weekDays2 = {"Sun","Mon","Tue","Wed","Thu","Fri","Sat"};

It is possible to declare an array variable without initialization, but you must use thenew operator when you assign an array to this variable. For example:

int[] array3;

array3 = newint[] { 1, 3, 5, 7, 9 }; // OK

array3 = {1, 3, 5, 7, 9}; // Error

2. VALUE TYPE AND REFERENCE TYPE ARRAYS

Consider the following array declaration:

SomeType[] array4 = new SomeType[10];

The result of this statement depends on whether SomeType is a value type or areference type.

If it is a value type, the statement creates an array of 10 instances of the typeSomeType.

If SomeType is a reference type, the statement creates an array of 10 elements, eachof which is initialized to a null reference.

3. MULTIDIMENSIONAL ARRAYS

Arrays can have more than one dimension. For example, the following declarationcreates a two-dimensional array of four rows and two columns:

int[,] array = newint[4, 2];

Also, the following declaration creates an array of three dimensions, 4, 2, and 3:

int[, ,] array1 = newint[4, 2, 3];


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MULTIDIMENSIONAL ARRAY INITIALIZATION

Initialize the array upon declaration as shown in the following example:

int[,] array2D = newint[,] {{1,2},{3,4},{5,6},{7,8}};

int[, ,] array3D = newint[,,] {{{1,2,3}},{{4,5,6}}};

You can also initialize the array without specifying the rank:

int[,] array4 = { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } };

If you choose to declare an array variable without initialization, you must use the newoperator to assign an array to the variable. For example:

int[,] array5;

array5 = newint[,] {{1,2},{3,4},{5,6},{7,8}}; // OK

array5 = {{1,2},{3,4},{5,6},{7,8}}; // Error

You can also assign a value to an array element, for example:

array5[2,1] = 25;

The following code example initializes the array variables to default (except forjagged arrays):

int[,] array6 = newint[10, 10];

4. JAGGED ARRAYS

A jagged array is an array whose elements are arrays.

The elements of a jagged array can be of different dimensions and sizes.

A jagged array is sometimes called an "array of arrays."

The following is a declaration of a single-dimensional array that has three elements,each of which is a single-dimensional array of integers:

int[][] jaggedArray = newint[3][];

Before you can use jaggedArray, its elements must be initialized. You can initialize

the elements like this:

jaggedArray[0] = newint[5];



Each of the elements is a single-dimensional array of integers.

The first element is an array of 5 integers, the second is an array of 4 integers, and thethird is an array of 2 integers.

It is also possible to use initializers to fill the array elements with values, in whichcase you do not need the array size. For example:


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jaggedArray[0] = newint[] { 1, 3, 5, 7, 9 };

jaggedArray[1] = newint[] { 0, 2, 4, 6 };

jaggedArray[2] = newint[] { 11, 22 };

You can also initialize the array upon declaration like this:

int[][] jaggedArray2 = newint[][]

{newint[] {1,3,5,7,9},

newint[] {0,2,4,6},

newint[] {11,22}

};

You can use the following shorthand form. Notice that you cannot omit the newoperator from the elements initialization because there is no default initialization for

the elements:

int[][] jaggedArray3 = {

newint[] {1,3,5,7,9},

newint[] {0,2,4,6},newint[] {11,22}

};

A jagged array is an array of arrays, and therefore its elements are reference types andare initialized to null.

You can access individual array elements like these examples:

// Assign 77 to the second element ([1]) of the first array

([0]):

jaggedArray3[0][1] = 77;

// Assign 88 to the second element ([1]) of the third array

([2]):

jaggedArray3[2][1] = 88;

It is possible to mix jagged and multidimensional arrays. The following is adeclaration and initialization of a single-dimensional jagged array that contains two-

dimensional array elements of different sizes:

int[][,] jaggedArray4 = newint[3][,]

{

newint[,] { {1,3}, {5,7} },

newint[,] { {0,2}, {4,6}, {8,10} },

newint[,] { {11,22}, {99,88}, {0,9} }

};

You can access individual elements as shown in this example, which displays thevalue of the element [1,0] of the first array (value 5):

System.Console.Write("{0}", jaggedArray4[0][1, 0]);

The method Length returns the number of arrays contained in the jagged array. Forexample, assuming you have declared the previous array, this line:

System.Console.WriteLine(jaggedArray4.Length);


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USING FOREACH WITH ARRAYS

C# also provides the foreach statement. This statement provides a simple, clean way toiterate through the elements of an array. For example, the following code creates an array

called numbers and iterates through it with the foreach statement:

int[] numbers = { 4, 5, 6, 1, 2, 3, -2, -1, 0 };foreach (int i in numbers)

{

System.Console.WriteLine(i);

}

With multidimensional arrays, you can use the same method to iterate through the elements,for example:

int[,] numbers2D = newint[3, 2] { { 9, 99 }, { 3, 33 }, { 5, 55 } };

foreach (int i in numbers2D)

{

System.Console.Write("{0} ", i);}

However, with multidimensional arrays, using a nested for loop gives you more control overthe array elements.

PASSING ARRAYS AS PARAMETERS

Arrays may be passed to methods as parameters. As arrays are reference types, the method

can change the value of the elements. Passing single-dimensional arrays as parameters

You can pass an initialized single-dimensional array to a method. For example:

PrintArray(theArray);

The method called in the line above could be defined as:

void PrintArray(int[]arr)

{

//method code

}

You can also initialize and pass a new array in one step. For example:

PrintArray(newint[] { 1, 3, 5, 7, 9 });


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PASSING MULTIDIMENSIONAL ARRAYS AS PARAMETERS

You can pass an initialized multidimensional array to a method. For example, if theArrayis a two dimensional array:

PrintArray(theArray);

The method called in the line above could be defined as:

void PrintArray(int[,]arr)

{

//method code

}

You can also initialize and pass a new array in one step. For example:

PrintArray(newint[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } });


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Statements

THE IFSTATEMENT

You can selectively execute part of a program through the if statement. Its simplest form isshown here:

if(condition)

statement;

Condition is a Boolean (that is, true or false) expression. If condition is true, then the statement

is executed. If condition is false, then the statement is bypassed. The complete form of the if

statement is:

if(condition)

statement;

elsestatement;

The general form of the if using blocks of statements is:

if(condition)

{

statement sequence;

}

else

{

statement sequence;

}

//if-else-if ladder. It looks like this:

if(condition)

statement;

elseif(condition)

statement;

elseif(condition)

statement;

.

.

.else

statement;


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THE SWITCHSTATEMENT

The switch expression must be of an integer type, such as char, byte, short, or int, or of typestring.

The default statement sequence is executed if no case constant matches the expression.

The default is optional.

If default is not present, no action takes place if all matches fail. When a match is found, the statements associated with that case are executed until the break

is encountered.

The general form of the switch statement is:

switch(expression)

{

case constant1:

statement sequence;

break;

case constant2:

statement sequence;

break;

case constant3:

statement sequence;

break;

.

.

.

default:

statement sequence;

break;

}

USE GOTO WITH A SWITCH

The goto is C#'s unconditional jump statement.

When encountered, program flow jumps to the location specified by the goto.

The goto requires a label for operation.

A label is a valid C# identifier followed by a colon.


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Example-01:

using System;

classSwitchGoto

{


{

for (int i = 1; i < 5; i++){

switch (i)

{

case 1:

Console.WriteLine("In case 1");

gotocase 3;

case 2:


gotocase 1;

case 3:


gotodefault;

default:Console.WriteLine("In default");

break;

}

Console.WriteLine();

}

}

}


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Loops

THE FOR LOOP

for loop you can repeatedly execute a sequence of code by creating a loop. The general formof the for loop for repeating a single statement is:

for(initialization; condition; iteration)

statement;

//For repeating a block, the general form is

for(initialization; condition; iteration)

{

statement sequence

}

Example-01:

using System;

classMainClass

{


{

int count;

for (count = 0; count < 5; count = count + 1)

Console.WriteLine("This is count: " + count);

Console.WriteLine("Done!");

}

}

THE FOREACH LOOP

The foreach loop is used to cycle through the elements of a collection. The general form of

foreach is shown here:

foreach(type var-name in collection)

statement;

THE DO WHILE LOOP

Do while loop A do-while loop will always execute at least once. The general form of the do-

while loop is:

do

{

statements;

}while(condition);


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Hello World My First Program

using System;

// A "Hello World!" program in C#

namespace HelloWorld

{

classHello

{staticvoid Main()

{

System.Console.WriteLine("Hello World!");

}

}

}

COMMENTS

// A "Hello World!" program in C#

The characters//convert the rest of the line to a comment. You can also comment a block of

text by enclosing it between the/* and */characters, for example:

THE MAIN METHOD

C# programs generally use the input / output services provided by the run-time library of the.NET Framework.

The statement, System.Console.WriteLine("Hello World!"); uses the WriteLine method,one of the output methods of the Console class in the run-time library.

It displays its string parameter on the standard output stream followed by a new line. OtherConsole methods are used for different input and output operations.

If you include the using System; directive at the beginning of the program, you can directlyuse the System classes and methods without fully qualifying them.

For example, you can call Console.WriteLine instead, without specifyingSystem.Console.Writeline:


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COMPILATION AND EXECUTION

You can compile the "Hello World!" program either by creating a project in the Visual

Studio IDE, or by using the command line. Use the Visual Studio Command Prompt or invoke

vsvars32.bat to put the Visual C# tool set on the path in your command prompt.

To compile the program from the command line:

Create the source file by using any text editor and save it using a name such as Hello.cs. (C# source code files use the extension .cs).

To invoke the compiler, enter the command:csc Hello.cs

If your program does not contain any compilation errors, a Hello.exe file will be created.

To run the program, enter the command:Hello

SAMPLE COMMAND LINES

1. Compiles File.cs producing File.exe:csc File.cs

2. Compiles File.cs producing File.dll:csc /target:library File.cs

3. Compiles File.cs and creates My.exe:

csc /out:My.exe File.cs

4. Compiles all the C# files in the current directory, with optimizations on and defines theDEBUG symbol. The output is File2.exe:

csc /define:DEBUG /optimize /out:File2.exe *.cs

5. Compiles all the C# files in the current directory producing a debug version of File2.dll. Nologo and no warnings are displayed:

csc /target:library /out:File2.dll /warn:0 /nologo /debug *.cs

6. Compiles all the C# files in the current directory to Something.xyz (a DLL):csc /target:library /out:Something.xyz *.cs


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Introduction to Object Oriented programming (OOP)

OBJECT-ORIENTED THE MIRRORS REAL WORLD

Consider real world situations involving things (objects) and actions (procedures). We consider the object first, and then what action is appropriate.

For example, we select an object (apple) and then the action (eats, peel, sell, move, etc).

We do not think of an action (move) and then look around for an object.

INTRODUCTION

Object-Oriented Programming (OOP) is a replacement for conventional programming.

It is a new way of organizing and developing programs and has nothing to do with anyparticular language.

However, not all languages are suitable to implement the OOP concepts easily. There is a good reason for this transformation. OOP offers several benefits, such as easy

code maintenance, extensibility, and code reuse, not found in procedural programming

languages.

Languages that support OOP features are Smalltalk, Objective C, C++, Ada and ObjectPascal and VB.net etc.

C++ was created as an extension of C to support OOP.

Java, one of the most popular languages on the planet, is also an OOP language.

THE BENEFITS OF OOPS

1. Extensibility:

OOP naturally supports extensibility. Having a class with certain functionality, you can

quickly extend that class to create a different class with extended functionality.

2. Code Reuse:

Since functionality is encapsulated into a class and each class is an independent entity,

providing a library is very easy. In fact, programmers of any .NET Framework language

can and should use the .NET Framework class library, an extensive library that providesrich functionality. Better still, you can extend the functionality of the class library to

provide classes that suit your needs.


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CLASSES

Classes are the main focus in OOP.

Simply put, a class is a data type that provides some functionality.

A class is a template that defines the form of an object.

A class specifies both the data and the code that will operate on that data.

Objects are instances of a class. The methods and variables that constitute a class are called members of the class.

THE GENERAL FORM OF A CLASS

// A class is created by use of the keyword class.

classclassname

{

// declare instance variables

access type var1;

access type var2;

// ...

access type varN;

// declare methods

access ret-type method1(parameters)

{

// body of methodu160 ?

}

access ret-type method2(parameters)

{

// body of method

}

// ...

access ret-type methodN(parameters)

{

// body of method

}

}

The general form for declaring an instance variable is shown here:

access type varN;

access specifies the access,

type specifies the type of variable, and var-name is the variable's name.

To access these variables, you will use the dot (.) operator.

The dot operator links the name of an object with the name of a member.

The general form of the dot operator is shown here:

object.member;

You can use the dot operator to access both instance variables and methods.


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// A Simple Class showing class definition syntax

classMyClass

{

int simpleValue = 0;

}

CONSTRUCTOR

constructor to class A constructor initializes an object when it is created.

A constructor has the same name as its class.

A constructor is syntactically similar to a method.

Constructors have no explicit return type.

The general form of constructor is shown here:

access class-name()

{

// constructor code}

DESTRUCTOR

A destructor method called just prior to an object's final destruction by the garbagecollector.

A destructor can be used to ensure that an object terminates cleanly.

Destructors have this general form:

~class-name()

{

// destruction code

}


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ACCESS SPECIFIERS

C#'s Access Specifies An access specifies determines how other parts of a program canaccess a class member.

Member access is controlled by four access specifies:o Public.

o Private.o Protected.o Internal.

Public member can be accessed by any other code in your program.

Main() is declared as public because it will be called by code outside of its class (theoperating system).

Private member can be accessed only by other members of its class.

A Protected member is public within a class hierarchy, but private outside that hierarchy.

A Protected member is created by using the protected access modifier.

The internal modifier declares that a member is known throughout all files in an assembly,but unknown outside that assembly.

The protected internal access level can be given only to class members.

A member declared with protected internal access is accessible within its own assembly orto derived types.


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OOP Concepts

KEY CONCEPTS OF OBJECT ORIENTATION

1. Abstraction.2. Encapsulation.3. Polymorphism.4. Inheritance.

ABSTRACTION

Abstraction is the ability to generalize an object as a data type that has a specific set ofcharacteristics and is able to perform a set of actions.

Object-oriented languages provide abstraction via classes. Classes define the properties and

methods of an object type.

Examples:

You can create an abstraction of a dog with characteristics, such as color, height, and weight,

and actions such as run and bite.

The characteristics are called properties, and the actions are called methods.

A Recordset object is an abstract representation of a set of data.

Classes are blueprints for Object.

Objects are instance of classes.

// C# Example of Class:

publicclassDraw

{

// Class code.

}

OBJECT REFERENCES

When we work with an object we are using a reference to that object. On the other hand, whenwe are working with simple data types such as Integer, we are working with the actual value

rather than a reference.

When we create a new object using the New keyword, we store a reference to that object ina variable. For instance:

Draw MyDraw = new Draw;

This code creates a new instance of Draw.

We gain access to this new object via the MyDraw variable. This variable holds a reference

to the object.


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Now we have a second variable, which also has a reference to that same object.

We can use either variable interchangeably, since they both reference the exact same object.

The thing we need to remember is that the variable we have is not the object itself but,rather, is just a reference or pointer to the object itself.

EARLY BINDING

Early binding means that our code directly interacts with the object, by directly calling itsmethods.

Since the compiler knows the object's data type ahead of time, it can directly compile codeto invoke the methods on the object.

Early binding also allows the IDE to use IntelliSense to aid our development efforts;

it allows the compiler to ensure that we are referencing methods that do exist and that weare providing the proper parameter values.

LATE BINDING

Late binding means that our code interacts with an object dynamically at run-time.

This provides a great deal of flexibility since our code literally doesn't care what type ofobject it is interacting with as long as the object supports the methods we want to call.

Because the type of the object isn't known by the IDE or compiler, neither IntelliSense norcompile-time syntax checking is possible but we get unprecedented flexibility in exchange.

If we enable strict type checking by using Option Strict On at the top of our code modules,then the IDE and compiler will enforce early binding behavior.

By default, Option Strict is turned off and so we have easy access to the use of late binding

within our code.

INHERITANCE

In the real world there are many objects that can be specialized.

In OOP, a parent class can inherit its behavior and state to children classes.

This concept was developed to manage generalization and specialization in OOP and isrepresented by a is-a relationship.

The following OO terms are commonly used names given to parent and child classes in

OOP:

o Superclass: Parent class.o Subclass: Child class.o Base class: Parent class.o Derived class: Child class

The most common real world sample to explain inheritance is the geometric shapes objectmodel. Squares, circles, triangles, rectangles, pentagons, hexagons, and octagons are

geometric shapes.


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The following figure shows a sample set of geometric figures:

The concept of generalization in OOP means that an object encapsulates common state anbehavior for a category of objects.

The general object in this sample is the geometric shape. Most geometric shapes have area, perimeter, and color.

The concept of specialization in OOP means that an object can inherit the common state andbehavior of a generic object; however, each object needs to define its own special and

particular state an behavior.

In Figure 1, each shape has its own color. Each shape has also particular formulas tocalculate its area and perimeter.

Inheritance makes code elegant and less repetitive.

If we know that all shapes have color, should we program a color attribute for each shape?The answer is no! Would it be a better idea to create a shape class that has a color attribute

and to make all the specialized shapes to inherit the color attribute? The answer is yes!

An object model for this sample could have a shape parent class and a derived class for eachspecific shape.

The following UML class diagram shows the set of classes needed to model the geometricshapes sample. Observe the field, properties, and methods for each class:

Figure 1


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Figure 2. The Shape class is the parent class.

Square, Rectangle, and Circle are derived classes that inherit from Shape. The triangle-connector in the diagram represents an is-a relationship.

The .NET framework has many base classes. Everything is derived from System.Object.

You can create almost anything you imagine using the built-in functionality provided in the

.NET Framework Class Library.

To create a derived class in C#, the class declaration should be done as:

class child: parent

To create a derived class in VB.NET, the class declaration should be done as:

Class child

Inherits parent

End Class

Figure 2


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MULTIPLE INHERITANCES

Multiple inheritances is the possibility that a child class can have multiple parents.

Human beings have always two parents, so a child will have characteristics from bothparents.

In OOP, multiple inheritances might become difficult to handle because it allows ambiguity

for the compiler. There are programming languages such as C++ that allow multiple inheritances; however,

other programming languages such as Java and the .NET Framework languages do not

allow multiple inheritances.

Multiple inheritances can be emulated in .NET using Multiple Interface Inheritance.


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Structured Query Language (SQL)

WHAT IS SQL?

SQL stands for Structured Query Language. SQL lets you access and manipulate databases.

SQL is an ANSI (American National Standards Institute) standard.

WHAT CAN SQL DO?

SQL can execute queries against a database.

SQL can retrieve data from a database.

SQL can insert records in a database.

SQL can update records in a database.

SQL can delete records from a database

SQL can create new databases.

SQL can create new tables in a database.

SQL can create stored procedures in a database.

SQL can create views in a database.

SQL can set permissions on tables, procedures, and views.

SQL IS A STANDARD BUT

Although SQL is an ANSI (American National Standards Institute) standard, there are manydifferent versions of the SQL language.

However, to be compliant with the ANSI standard, they all support at least the majorcommands (such as SELECT, UPDATE, DELETE, INSERT, WHERE) in a similar

manner.

Note: Most of the SQL database programs also have their own proprietary extensions inaddition to the SQL standard!

RDBMS

RDBMS stands for Relational Database Management System.

RDBMS is the basis for SQL, and for all modern database systems like MS SQL Server,IBM DB2, Oracle, MySQL, and Microsoft Access.

The data in RDBMS is stored in database objects called tables.

A table is a collection of related data entries and it consists of columns and rows.


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THE SQLSELECTSTATEMENT

The SELECT statement is used to select data from a database.

The result is stored in a result table, called the result-set.

SQL SELECTSyntax

SELECT column_name(s)

FROM table_name

Or

SELECT * FROM table_name

THE SQLSELECTDISTINCTSTATEMENT

In a table, some of the columns may contain duplicate values. This is not a problem,however, sometimes you will want to list only the different (distinct) values in a table.

The DISTINCT keyword can be used to return only distinct (different) values.

SQL SELECT DISTINCTSyntax

SELECT DISTINCT column_name(s)

FROM table_name

THE WHERECLAUSE

The WHERE clause is used to extract only those records that fulfill a specified criterion.

SQL WHERE Syntax


FROM table_name

WHERE column_name operator value


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OPERATORS ALLOWED IN THE WHERECLAUSE

Operator Description

= Equal

Not equal

> Greater than

< Less than

>= Greater than or equal


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THE ORDERBY KEYWORD

The ORDER BY keyword is used to sort the result-set by a specified column.

The ORDER BY keyword sort the records in ascending order by default.

If you want to sort the records in a descending order, you can use the DESC keyword.

SQL ORDER BYSyntax


FROM table_name

ORDER BY column_name(s) ASC | DESC

THE INSERTINTOSTATEMENT

The INSERT INTO statement is used to insert a new row in a table.

It is possible to write the INSERT INTO statement in two forms.

The first form doesn't specify the column names where the data will be inserted, only theirvalues:

SQLINSERT INTO Syntax

INSERT INTO table_name

VALUES (value1, value2, value3,...)

The second form specifies both the column names and the values to be inserted:

INSERT INTO table_name (column1, column2, column3,...)VALUES (value1, value2, value3,...)

THE UPDATESTATEMENT

The UPDATE statement is used to update existing records in a table.

SQL UPDATE Syntax

UPDATE table_nameSET column1=value, column2=value2,...

WHERE some_column = some_value

Note: The WHERE clause specifies which record or records that should be updated. If youomit the WHERE clause, all records will be updated!


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THE DELETESTATEMENT

The DELETE statement is used to delete rows in a table.

SQLDELETE Syntax

DELETE FROM table_nameWHERE some_column = some_value

Note: The WHERE clause specifies which record or records that should be deleted. If youomit the WHERE clause, all records will be deleted!

DELETE ALL ROWS

It is possible to delete all rows in a table without deleting the table. This means that the tablestructure, attributes, and indexes will be intact:

SQLDELETE Syntax

DELETE FROM table_name

Or

DELETE * FROM table_name

Note: Be very careful when deleting records. You cannot undo this statement!

THE LIKEOPERATOR

The LIKE operator is used to search for a specified pattern in a column.

SQLLIKE Syntax


FROM table_name

WHERE column_name LIKE pattern

THE CREATEDATABASESTATEMENT

The CREATE DATABASE statement is used to create a database.

SQL CREATE DATABASE Syntax

CREATE DATABASE database_name


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THE CREATETABLESTATEMENT

The CREATE TABLE statement is used to create a table in a database.

SQL CREATE TABLE Syntax

CREATE TABLE table_name(

column_name1 data_type,



....

)

THE ALTERTABLESTATEMENT

The ALTER TABLE statement is used to add, delete, or modify columns in an existingtable.

SQLALTER TABLE Syntax

To add a column in a table, use the following

ALTER TABLE table_name

ADD column_name datatype

To delete a column in a table, use the following syntax (notice that some database systemsdon't allow deleting a column):


DROP COLUMN column_name

To change the data type of a column in a table, use the following syntax:


ALTER COLUMN column_name datatype


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SQLCONSTRAINTS

Constraints are used to limit the type of data that can go into a table.

Constraints can be specified when a table is created (with the CREATE TABLE statement)or after the table is created (with the ALTER TABLE statement).

We will focus on the following constraints:

o NOT NULL:

The NOT NULL constraint enforces a column to NOT accept NULL values.

The NOT NULL constraint enforces a field to always contain a value. Thismeans that you cannot insert a new record, or update a record without

adding a value to this field.

o UNIQUE:

The UNIQUE constraint uniquely identifies each record in a database table.

The UNIQUE and PRIMARY KEY constraints both provide a guarantee foruniqueness for a column or set of columns.

A PRIMARY KEY constraint automatically has a UNIQUE constraintdefined on it.

Note: that you can have many UNIQUE constraints per table, but only onePRIMARY KEY constraint per table.

Example : SQL Server / Oracle / MS Access:

CREATE TABLE Persons

(P_Id int NOT NULL UNIQUE,

LastName varchar(255) NOT NULL,

FirstName varchar(255),

Address varchar(255),

City varchar(255)

)

To allow naming of a UNIQUE constraint, and for defining a UNIQUEconstraint on multiple columns, use the following SQL syntax:


(

P_Id int NOT NULL,




City varchar(255),

CONSTRAINT uc_PersonID UNIQUE (P_Id,LastName)

)


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o PRIMARY KEY:

The PRIMARY KEY constraint uniquely identifies each record in a databasetable.

Primary keys must contain unique values.

A primary key column cannot contain NULL values.

Each table should have a primary key, and each table can have only oneprimary key.


(

P_Id int NOT NULL PRIMARY KEY,




City varchar(255)

)

To allow naming of a PRIMARY KEY constraint, and for defining aPRIMARY KEY constraint on multiple columns, use the following SQL

syntax:


(

P_Id int NOT NULL,



Address varchar(255),City varchar(255),

CONSTRAINT pk_PersonID PRIMARY KEY (P_Id,LastName)

o FOREIGN KEY:

A FOREIGN KEY in one table points to a PRIMARY KEY in another table.

The FOREIGN KEY constraint is used to prevent actions that would destroylink between tables.

The FOREIGN KEY constraint also prevents that invalid data is inserted intothe foreign key column, because it has to be one of the values contained in

the table it points to.

CREATE TABLE Orders

(

O_Id int NOT NULL PRIMARY KEY,

OrderNo int NOT NULL,

P_Id int FOREIGN KEY REFERENCES Persons(P_Id)

)

o CHECKo DEFAULT


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MICROSOFT ACCESS DATA TYPES

Data type Description Storage

TextUse for text or combinations of text and numbers. 255 characters

maximum

MemoMemo is used for larger amounts of text. Stores up to 65,536 characters.

Note: You cannot sort a memo field. However, they are searchable

Byte Allows whole numbers from 0 to 255 1 byte

Integer Allows whole numbers between -32,768 and 32,767 2 bytes

Long Allows whole numbers between -2,147,483,648 and 2,147,483,647 4 bytes

Single Single precision floating-point. Will handle most decimals 4 bytes

Double Double precision floating-point. Will handle most decimals 8 bytes

CurrencyUse for currency. Holds up to 15 digits of whole dollars, plus 4 decimal

places. Tip: You can choose which country's currency to use8 bytes

AutoNumber AutoNumber fields automatically give each record its own number,usually starting at 1

4 bytes

Date/Time Use for dates and times 8 bytes

Yes/No

A logical field can be displayed as Yes/No, True/False, or On/Off. In code,

use the constants True and False (equivalent to -1 and 0). Note: Null

values are not allowed in Yes/No fields

1 bit

Ole Object Can store pictures, audio, video, or other BLOBs (Binary Large OBjects)up to

1GB

Hyperlink Contain links to other files, including web pages

Lookup

Wizard

Let you type a list of options, which can then be chosen from a drop-down

list4 bytes


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SQLSERVER DATA TYPES :CHARACTER STRINGS

Data type Description Storage

char(n)Fixed-length character string. Maximum 8,000

charactersn

varchar(n)Variable-length character string. Maximum

8,000 characters

varchar(max)Variable-length character string. Maximum

1,073,741,824 characters

textVariable-length character string. Maximum 2GB

of text data

intAllows whole numbers between -2,147,483,648and 2,147,483,647

4 bytes

float(n)

Floating precision number data from -1.79E +

308 to 1.79E + 308.The n parameter indicates

whether the field should hold 4 or 8 bytes.

float(24) holds a 4-byte field and float(53) holds

an 8-byte field. Default value of n is 53.

4 or 8 bytes

datetime From January 1, 1753 to December 31, 9999with an accuracy of 3.33 milliseconds

Dip. C Sharp Dot Net

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