Ist Lecture on C++

7/31/2019 Ist Lecture on C++

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Structure of a C++ Program

Date: 17/01/11


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Outlines

Introduction

Components of a C++ Program

Escape Sequences Variable declaration & Memory allocation

Namespaces

User Interactive Programs Formatting the Output


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Introduction

C++ improves on many of Cs features.

C++ provides object-oriented programming(OOP). C++ is a superset to C.


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History

C was designed by Ritchi, Tompson, Kernighan

It was fast, good & powerful

but programs maintance was a nightmare!

Solution: ... Object-Oriented Programming


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Some New Operators in C++

>> Extraction Operator extracts data from

input stream.


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Components of C++ program

Header files

INT MAIN() or VOID MAIN()

Output Statement- Use Of COUT

The CIN


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Simple C++ Program

#include

int main()

{Std :: cout


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HEADER FILES

#include

#include #include


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INT MAIN OR VOID MAIN

#include

int main()

{Statements ;

If(expression)

{statement ;

---------------;

}

Statement ; // commentreturn 0 ;

}


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Output Statements

The first output statement of previous programstd :: cout


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Using cout and Insertion operator

Screen

cout


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Some character preceded by slash character(\)

like the one at the end of the above output

statement, i.e. \n having a special meaning

for the compiler.

Back Slash (\) is an escape character.

\n is new line character.

Thus, std::cout


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Escape Character Description of action

\a Bell or beep is generated by the computer on

program execution.

\b Back space. Move cursor to previous position

\f From feed Advance cursor to next page

\n Shift to next line

\r Carriage return. Position the cursor to the

beginning of current line.

\t Horizontal tab.

\v Vertical tab.

\\ Displays a back slash character (\)

\ Displays a single quote character()

\? Displays a question mark(?).\0 Null termination character. Signifies end of a

character string.

\o Code for octal numbers.

\x Code for hexadecimal numbers respectively

\ Displays a double quote character().


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Application of some escape sequence

#include

int main()

{

std::cout


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Output

The expected output is :

Hello, Welcome to programming with C++!

Hello,\ Welcome to programming with C++!\Hello Welcome to programming with C++!

Hello Welcome to programming with C++!


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Comments

A comment introduced by first putting doubleslash (//) followed by the comment up to the endof the line.

If the comment is long and goes to the next line,another double slash (//) is needed before thenext line.

Alternatively, a long comment may as wellas be

between the C type comment symbols,i.e. /*before the start of comment and */ at the end ofthe comment.


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How to include comments and use of

void main() in place of int main()// A program with comments

#include

Void main()

// Anything written after double slash is neglected up to the

// end of line. The comment can be put anywhere in the program.

{std::cout


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The cin

To put in some data we make use of function cin

This is used along with the operator >> which is

called extraction operator.

This is followed by the name of variable in whose

memory block the data has to be stored.

After typing the data for cin, do press the enter-

key, otherwise, the computer will not proceedfurther.


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Using cin and Extraction operator

cin >> number

Keyboard


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Application of cin in a user interactive

program

#include

int main()

{

int length = 0 ; // length is the name of variable of type intInt width = 0, area =0; // width and area are also names of variables

std:: cout


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Namespaces

It enables the programmer to group a set ofobjects or function under one name.

All classes, objects and functions of C++

Standard Library are defined undernamespace std.

We can simplify the writing ofstd :: coutto

coutand std :: cin to cin by including followingthe directive in the program:

using namespace std ;


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Application of namespaces

#include

Using namespace std ; // use of std

namespace

namespace NS1 // no semicolon at the end

of line

{

int n = 3 ;

float m = 2.5 ;

int k = 2 ;

double R = n*m*k ; }

namespase NS2 // no semicolon at the end of

line{ float n = 4.0 ; // Names are same as in NS1

//but values are different .

int m =2 ;

double k = 3.0 ;

double R = n*m*k ; }

int main()

{ int Squatre ;

int Product ;

using namespace NS2 ;

Square = n*n + m*m ; // values under NS2 are used

Product = NS1 :: k*NS2 :: m ; // k belongs to NS1 and//m to NS2

cout


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User Interactive Programs

#include

using namespace std ;

int main()

{ int D ;

float PI ;

// Here D stands for//diameter and PI stands

//for .

double A , C ;

// A stands for area and C

//stands for circumference

cout > D >> PI ;

// statement for input D and PI

cout


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Formatting The Output

In next Class ..


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Conclusion

We tried to grasp the fundamentals of C++

programming.


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Thanks for listening.

Documents

Ist Lecture on C++