Introduction to C++ An object-oriented language Unit - 01.

Introduction to Introduction to C++C++

An object-oriented languageAn object-oriented language

Unit - 01Unit - 01

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Unit IntroductionUnit Introduction

This unit covers the basics of C++ This unit covers the basics of C++ languagelanguage

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Unit ObjectivesUnit Objectives

After covering this unit you will After covering this unit you will understand…understand…

Introduction to C++Introduction to C++ Program structure in C++Program structure in C++ Data typesData types Specifiers and modifiers Specifiers and modifiers Scope and storage allocationScope and storage allocation OperatorsOperators FunctionsFunctions

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IntroductionIntroduction

‘‘B’ languageB’ language ‘‘B’ expanded to ‘C’ languageB’ expanded to ‘C’ language The ‘C++’ programming languageThe ‘C++’ programming language

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Header Files (.h)Header Files (.h)

An interface of an implementation to An interface of an implementation to the clientthe client

Main contents of a header fileMain contents of a header file Declarations of classes and structuresDeclarations of classes and structures Other header files or libraries to be Other header files or libraries to be

includedincluded Global variablesGlobal variables

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Source Files (.cpp)Source Files (.cpp)

In general, implementation of the In general, implementation of the interface part (declared in .h file)interface part (declared in .h file)

.cpp file can also contain header file .cpp file can also contain header file contentscontents

Main contents of a source fileMain contents of a source file Implementation of class (and/or Implementation of class (and/or

structure) declared in header filestructure) declared in header file Can also have a main(), an entry point Can also have a main(), an entry point

to the executable programto the executable program

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Executing C++ ProgramExecuting C++ Program

Search the included librariesSearch the included libraries Compile the related code into .obj Compile the related code into .obj

formform Link the complied code to an Link the complied code to an

executable codeexecutable code Execute the codeExecute the code

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Hello World ProgramHello World Program// hello.cpp// hello.cpp

#include <iostream.h>#include <iostream.h>

#include “myfile.h”#include “myfile.h” // user defined header file// user defined header file

int gVariable = 100;int gVariable = 100; // global variables// global variables

void main () void main ()

{{

cout << “Hello World!”;cout << “Hello World!”; // printing Hello World on// printing Hello World on

// console// console

}}

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NameSpacesNameSpaces

Solve naming problems in large Solve naming problems in large applicationsapplications

using and namespaceusing and namespace keywords are keywords are used to declare and define a name used to declare and define a name space e.g.space e.g.

using namespace std;using namespace std;

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Example: NameSpacesExample: NameSpaces// create namespace 'NSfromAccount'// create namespace 'NSfromAccount'namespace NSfromAccount namespace NSfromAccount {{ int accountNumber = 2000;int accountNumber = 2000;};};

// create namespace 'NStoAccount'// create namespace 'NStoAccount'namespace NStoAccount namespace NStoAccount {{ int accountNumber = 3000;int accountNumber = 3000;};};

void main()void main(){{ // local variable // local variable int accountNumber = 100;int accountNumber = 100;

// using accountNumber of namespace 'NSfromAccount'// using accountNumber of namespace 'NSfromAccount' cout << NSfromAccount::accountNumber << endl; cout << NSfromAccount::accountNumber << endl;

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Example: NameSpaces (contd.)Example: NameSpaces (contd.)

// using accountNumber of namespace 'NStoAccount'// using accountNumber of namespace 'NStoAccount' cout << NStoAccount::accountNumber << endl; cout << NStoAccount::accountNumber << endl;

// using local variable accountNumber// using local variable accountNumber cout << accountNumber << endl; cout << accountNumber << endl; }}

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Data TypesData Types

Data Types provide a way you use a Data Types provide a way you use a memorymemory

Data Type have a storage size Data Type have a storage size associated with itassociated with it

C/C++ has the following data types:C/C++ has the following data types: charchar 8 bits 8 bits intint 16 bit 16 bit floatfloat single-precision single-precision double double-precisiondouble double-precision

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Data Types (contd.)Data Types (contd.)

boolbool true/false statetrue/false state enumenum values given to values given to

symbols/meaningful wordssymbols/meaningful words

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Example: Data TypesExample: Data Types#include <stdlib.h>#include <stdlib.h>

void main() void main()

{{

char characterVal = ‘a’;char characterVal = ‘a’;

int integerVal = 1;int integerVal = 1;

float floatVal = 2.3f;float floatVal = 2.3f;

double doubleVal = 3.567891;double doubleVal = 3.567891;

bool booleanVal = 1; bool booleanVal = 1; // true state// true state

enum ENumeratedVal = { ZERO, ONE, TWO };enum ENumeratedVal = { ZERO, ONE, TWO };

}}

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SpecifiersSpecifiers

Specifiers modify the meaning of the Specifiers modify the meaning of the basic data typesbasic data types

Four types of specifiersFour types of specifiers longlong shortshort signedsigned unsignedunsigned

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Specifiers (contd.)Specifiers (contd.)

Illegal specifier combinations are:Illegal specifier combinations are: long floatlong float short float short float short doubleshort double

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Example: SpecifiersExample: Specifiers#include <stdlib.h>#include <stdlib.h>

void main() void main()

{{

int intVar = 10; int intVar = 10; // standard integer format// standard integer format

short int shortVar = 10; short int shortVar = 10; // takes less space// takes less space

short shortVar2 = 10; short shortVar2 = 10; // you may omit the int// you may omit the int

long int longVar = 10; long int longVar = 10; // takes more space than int// takes more space than int

long longVar2 = 10; long longVar2 = 10; // you may omit the int// you may omit the int

unsigned int uIntVar = 10; unsigned int uIntVar = 10; // no sign bit reserved// no sign bit reserved

signed int intVar2 = -10; signed int intVar2 = -10; // same as int (sign bit// same as int (sign bit // reserved by default)// reserved by default)

}}

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ModifiersModifiers

Modifiers change the meaning, type, Modifiers change the meaning, type, scope or accessibility of the variable, scope or accessibility of the variable, function, structure or classfunction, structure or class

Modifiers supported by C/C++ are:Modifiers supported by C/C++ are: constconst staticstatic registerregister volatilevolatile friendfriend

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Example: ModifiersExample: Modifiers#include <stdlib.h>#include <stdlib.h>

void main() void main()

{{

const int CONST_VAR = 10; const int CONST_VAR = 10;

// this variable’s value cannot be changed and is final// this variable’s value cannot be changed and is final

static char* s_StaticString = “Hello”; static char* s_StaticString = “Hello”;

/* this variable is available throughout the program/* this variable is available throughout the program

length and is equivalent to a global variable */length and is equivalent to a global variable */

volatile float volatileVar = 10.3; volatile float volatileVar = 10.3;

/* no compiler optimisation is done on the variable, as/* no compiler optimisation is done on the variable, as

‘ ‘volatile’, its value is supposed to change frequentlyvolatile’, its value is supposed to change frequently

friend requires class declaration, and will friend requires class declaration, and will

be discussed later in the training program */be discussed later in the training program */

}}

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Scope and Storage Scope and Storage AllocationAllocation

Scope means where a variable can be Scope means where a variable can be accessibleaccessible

Storage allocation means the lifetime of Storage allocation means the lifetime of a variable and how the storage is a variable and how the storage is allocated by the compilerallocated by the compiler Global variablesGlobal variables Local variablesLocal variables Register variablesRegister variables Static variablesStatic variables External variablesExternal variables

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Example: Variables with different scope and Example: Variables with different scope and lifetimelifetime

#include <iostream.h>#include <iostream.h>

int gVar1;int gVar1; // define global variable// define global variable

extern int geVar1;extern int geVar1; // declare an extern variable// declare an extern variable

static int sCount = 100;static int sCount = 100; // static global variable// static global variable

void f()void f()

{{

int x;int x; // local variable declaration// local variable declaration

x = 100;x = 100; // local variable definition// local variable definition

static int y = 200;static int y = 200; // local static variable// local static variable

cout << y++ << endl << x++ << gVar1++ << endl << geVar1++ << cout << y++ << endl << x++ << gVar1++ << endl << geVar1++ << endl << sCount++ << endl;endl << sCount++ << endl;

}}

int geVar1;int geVar1; // define an external variable// define an external variable

void main() void main()

{{

gVar1 = 300;gVar1 = 300;

f();f();

f();f();

}}

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OperatorsOperators

Arithmetic Operators (+, -, *, /, =)Arithmetic Operators (+, -, *, /, =) Relational Operators (<, >, <=, >=, Relational Operators (<, >, <=, >=,

==, !=)==, !=) Logical Operators (&&, ||)Logical Operators (&&, ||) Bitwise Operators (&, |, ^, ~)Bitwise Operators (&, |, ^, ~) Shift Operators (<<, >>)Shift Operators (<<, >>) Unary Operators (-, ~)Unary Operators (-, ~) Ternary Operator (? :)Ternary Operator (? :)

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Operators (contd.)Operators (contd.)

a = a < b ? b : a; a = a < b ? b : a; // this is equivalent to max operator// this is equivalent to max operator

Comma OperatorComma Operatora = (b++, c++, d++); a = (b++, c++, d++);

sizeofsizeof Operator Operatorcout << sizeof (long);cout << sizeof (long);

CastingCastinglong longVal = (long) intVal;long longVal = (long) intVal;

Operator PrecedenceOperator Precedence

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Example: OperatorsExample: Operators#include <stdlib.h>#include <stdlib.h>

void main() void main()

{{

int a, b, c; int a, b, c; // declaration of variables// declaration of variables

b = 2;b = 2; // value assignment// value assignment

c = 3; c = 3;

a = (((b+c)*b)-c) / b;a = (((b+c)*b)-c) / b; // add, multiply, subtract// add, multiply, subtract

// etc.// etc.

if(((a < b) || (b >= c)) && (a > c)) if(((a < b) || (b >= c)) && (a > c)) // compare// compare

{ {

a = ~(b & ~c); a = ~(b & ~c);

}}

elseelse

{{

a >> b;a >> b; // a is right shifted b times// a is right shifted b times

cout << a;cout << a;

}}

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Example: Operators Example: Operators (contd.)(contd.)

d = a;d = a;

a = a < b ? b : a; a = a < b ? b : a; // a is assigned the greater value // a is assigned the greater value // between a & b // between a & b

a = (b++, c++, d++); a = (b++, c++, d++); // comma and increment operations// comma and increment operations

long longVal = (long) a; long longVal = (long) a; // casting from int to long// casting from int to long

cout << sizeof(long); cout << sizeof(long); // displaying the size of long// displaying the size of long

} } // end main// end main

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Type DefinitionType Definition

typedef suggests ‘type definition’ typedef suggests ‘type definition’ name aliasingname aliasing is a more accurate is a more accurate

descriptiondescriptiontypedef int* IntPtrType;typedef int* IntPtrType;

IntPtrType px, py; IntPtrType px, py; // p represents pointer type// p represents pointer type

Here int* is aliased to IntPtrTypeHere int* is aliased to IntPtrType

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FunctionsFunctions

Functions have Functions have parametersparameters processingprocessing return valuesreturn values

Functions perform operations on the Functions perform operations on the parameters passed to it and returns a parameters passed to it and returns a value e.g.value e.g.returnVal FunctionName (functionParameters) returnVal FunctionName (functionParameters)

{{

// perform some operations on parameters passed// perform some operations on parameters passed

return returnVal;return returnVal;

}}

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Parameter PassingParameter Passing

Parameters can be passed to a Parameters can be passed to a function in following waysfunction in following ways By ReferenceBy Reference By ValueBy Value

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Example: FunctionExample: Function#include <stdlib.h>#include <stdlib.h>

void ByValue(int intVar) void ByValue(int intVar)

{{

intVar = 9; intVar = 9; // passed as 5, and changes to 9 locally// passed as 5, and changes to 9 locally

}}

void ByReference(int& intVar) void ByReference(int& intVar)

{{

intVar = 5;intVar = 5;

}}

void main() void main()

{{

int j = 2;int j = 2;

ByReference(j); ByReference(j); // j changes to 5// j changes to 5

ByValue(j); ByValue(j); // j remains at 5// j remains at 5

cout << j; cout << j; // displays 5// displays 5

}}

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Unit SummaryUnit Summary

In this unit you have covered …In this unit you have covered … Introduction to C++Introduction to C++ Program structure in C++ Program structure in C++ Data typesData types Specifiers and modifiers Specifiers and modifiers Scope and storage allocationScope and storage allocation OperatorsOperators FunctionsFunctions