Structure of a C++ program



// my first program in C++

#include <iostream.h>

int main () { cout << " Hello World "; return 0; }


// this my first program in C++

//: All the lines beginning with two slash signs (//) are considered comments.

#include <iostream.h>

#: Sentences that begin with a pound sign (#) are directives for the preprocessor. They are not executable code lines but indications for the compiler.

include: to include.

iostream.h:

standard header file.

This specific file includes the declarations of the basic standard input-output library in C++, and it is included because its functionality is used later in the program.

int main ( can include arguments ) { The content of the main function }

Beginning of the main function declaration (begin their execution)

All C++ programs have a main function

In C++ all functions are followed by a pair of parenthesis () that, optionally, can include arguments.

The content of the main function immediately follows its formal declaration and it is enclosed between curly brackets ({}).

cout << "Hello World";

cout the standard output stream in C++ (usually the screen).

cout is declared in the iostream.h header file.

(;) signifies the end of the instruction and must be included after every instruction in any C++ program.

return 0;

The return instruction causes the main ( ) function finish and return the code that the instruction is followed by, in this case 0.

This it is most usual way to terminate a program that has not found any errors during its execution.

C++ programs end with a sentence similar to this.

Example:

// This is my first C++ program

/* It's about a hello program

you know what I am saying? */

#include <iostream.h>

int main ()

{

cout << "Hello Aziz!"; // :)

cout << "How are you?";

return 0;

}
 



aziz.



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