introduction to c++

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Introduction to Introduction to C++C++


Objectives of this sessionObjectives of this session

What is C++What is C++ A Simple ProgramA Simple Program Comments in C++Comments in C++ Output OperatorOutput Operator Input OperatorInput Operator Cascading of I/O OperatorCascading of I/O Operator Structure of a C++ ProgramStructure of a C++ Program


C++C++

C++ is an object-oriented programming C++ is an object-oriented programming language.language.

Developed by Bjarne Stroustrup at Developed by Bjarne Stroustrup at AT&T Bell Laboratories, USA in the AT&T Bell Laboratories, USA in the early 1980’s.early 1980’s.

Simule 67 + C language Simule 67 + C language C++ C++ 1997 November ANSI/ISO standards 1997 November ANSI/ISO standards

committee standardised C++.committee standardised C++. For developing editors, compilers, For developing editors, compilers,

databases, communication systems, etc.databases, communication systems, etc.


A Simple ProgramA Simple Program

C++ works by giving (separate) instructions C++ works by giving (separate) instructions to the computer. to the computer.

These instructions can be written as functions.These instructions can be written as functions. The primary function used in C++ is called The primary function used in C++ is called

mainmain. This means that every C++ program . This means that every C++ program should have the should have the main()main() function. Because a function. Because a function is an assignment, in order to perform function is an assignment, in order to perform its job, a function has a body. The body of a its job, a function has a body. The body of a function starts with an opening curly bracket function starts with an opening curly bracket "{" and closes with a closing curly bracket "}"."{" and closes with a closing curly bracket "}".


A Simple ProgramA Simple Program

// my first program in // my first program in C++C++

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

int main ( )int main ( )

{ {

cout << "Hello World!"; cout << "Hello World!";

return 0;return 0;

}}

Hello World! Hello World!

continue…


Comments in C++Comments in C++

The most basic documentation you have to The most basic documentation you have to perform is to put comments as much as you perform is to put comments as much as you can. Comments help you and other people can. Comments help you and other people who read your code to figure out what you who read your code to figure out what you were doing.were doing.

Comments are not read by the compiler Comments are not read by the compiler while executing your program. while executing your program.

C++ supports two ways to insert comments: C++ supports two ways to insert comments: o // line comment// line commento /* block comment */ /* block comment */


Comments in C++Comments in C++

// The hello.cpp program// The hello.cpp program// Include the iostream library// Include the iostream library#include <iostream.h>#include <iostream.h>int main( )int main( ){{/* Here is a simple sentence that I want to display /* Here is a simple sentence that I want to display when the program starts. It doesn't do much. I am when the program starts. It doesn't do much. I am planning to do more stuff in the future. */planning to do more stuff in the future. */cout << "Hi, this is my program!";cout << "Hi, this is my program!";return 0;return 0;}}// The end of my program// The end of my program

continue…


Output OperatorOutput Operator

cout << "Hi, this is my program!";cout << "Hi, this is my program!";

cout is a predefined object that represents cout is a predefined object that represents the standard output stream in C++, here the standard output stream in C++, here the standard output stream is screen.the standard output stream is screen.

screen

cout << C++ variable

Object Insertion Operator


Output OperatorOutput Operator

The operator << is called The operator << is called insertioninsertion or or put to put to operatoroperator..

It inserts ( or sends ) the contents of the variable on It inserts ( or sends ) the contents of the variable on its right to the object on its left.its right to the object on its left.

cout << "Hi, this is my program!";cout << "Hi, this is my program!";

cout << number ;cout << number ;

screen

cout << C++ variable

Object Insertion Operator

continue…


Input OperatorInput Operator

cin >> number1;cin >> number1;

cin is a predefined object that corresponds cin is a predefined object that corresponds to the standard input stream in C++, here to the standard input stream in C++, here the standard input stream is keyboard.the standard input stream is keyboard.

cin >> 50.55

Object Extraction Operator C++ variable

Keyboard


Input OperatorInput Operator

The operator >> is known as The operator >> is known as extractionextraction or or get fromget from operator. operator.

It extracts ( or takes ) the value from the It extracts ( or takes ) the value from the keyboard and assigns it to the variable on its keyboard and assigns it to the variable on its right.right.

cin >> 50.55

Object Extraction Operator C++ variable

Keyboard

continue…


Cascading of I/O Cascading of I/O OperatorsOperators

Multiple use of << or >> in one Multiple use of << or >> in one statement is called cascading.statement is called cascading.

eg:-eg:-

cout << “Sum = ” << sum << cout << “Sum = ” << sum << “\n”;“\n”;

cin >> number1 >> number2;cin >> number1 >> number2;


Structure of a C++ Structure of a C++ ProgramProgram

Better to organize a program file into three Better to organize a program file into three separate files.separate files.

o Class declarations in a header file.Class declarations in a header file.o Definition of member function in a separate file.Definition of member function in a separate file.o The main program that uses the class is placed in The main program that uses the class is placed in

a third file which includes the previous two files.a third file which includes the previous two files.

Include files

Class declaration

Member functions declaration

Main function program

introduction to c++

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