Structure of C++ Program

 Followings are the sections in the structure of a C++ Program

1.      Documentation Section

 

2.      Preprocessor Directives or Compiler Directives Section

 

a.      Link Section

 

b.      Definition Section

 

3.      Global Declaration Section

 

4.      Class declaration or definition

 

5.      Main ( )

             {

             Statement block;

             }

1) Documentation Section: In Documentation section we give the Heading, Comments and brief introductory description of the program. Comment statement is the non-executable statement.

Comment can be given in two ways:

       Single Line Comment: Comment can be given in single line by using"//".

Multiple Line Comment:Comment can be given in multiple lines starting by using "/*" and end with "*/ ".

2)  Preprocessor Directives: Preprocessor Directives are divided into two parts.

 

Link Section: 

In the Link Section, we can link the compiler function like cout<<, cin>>, sqrt ( ), , clrscr( ), with the INCLUDE subdirectory having header files like iostream.h, conio.h, math.h, ctype.h, etc. It becomes very useful during the compilation and the linkage phase.

 

The general syntax is: 

 #include <header file>

Definition Section: The second section is the Definition section by using which we can define a variable with its value. For this purpose define statement is used.

 

The general syntax is:

#define variable name value

For example:

#define PI 3.142

3)   Global Declaration Section: In this section, we declare some variables before starting of the main program or outside the main program. These variables are globally declared and used by the main function or sub function. These variables are called global variables.

 

4)   Class declaration or definition: in this section we declare the class. The general syntax or general form of the class declaration is as follows:

 

Class  <name of class>

{

Datammbers;

Functions ();

}

 

5)  Main (): main function is where a program starts execution.

 

Writing the First C++ Program:                              

// my first program in C++               // Comment Line

#include <iostream.h>                     // Preprocessor Directives

Void main()                                      // Main function/function definition

{                                                                             

cout << "Hello World!";                  // function body}

}