Structure of C Program

 The basic structure of a C program is divided into 6 parts which makes it easy to read, modify, document, and understand in a particular format. C program must follow the

 below-mentioned outline in order to successfully compile and execute. Debugging is easier in a well-structured C program. 

Sections of the C Program

There are 6 basic sections responsible for the proper execution of a program. Sections are mentioned below:

 

1.     Documentation

2.     Preprocessor Section

3.     Definition

4.     Global Declaration

5.     Main() Function

6.     Sub Programs

 

Documentation : This section consists of the description of the program, the name of the program, and the creation date and time of the program. It is specified at the start of the program in the form of comments. Documentation can be represented as: 

Ex:       // description, name of the program, programmer name, date, time etc.

 

Preprocessor Section : All the header files of the program will be declared in the preprocessor section of the program. Header files help us to access other’s improved code into our code

Ex:       #include<stdio.h>

            #include<math.h>

 

Definition: Preprocessor directives start with the ‘#’ symbol. The #define preprocessor is used to create a constant throughout the program. Whenever this name is encountered by the compiler, it is replaced by the actual piece of defined code.

 

Ex:    #define long X 10

 

Global declaration: The global declaration section contains global variables, function declaration, and static variables. Variables and functions which are declared in this scope can be used anywhere in the program. 

Main() Function: Every C program must have a main function. The main() function of the program is written in this section. Operations like declaration and execution are performed inside the curly braces of the main program. The return type of the main() function can be int as well as void too. void() main tells the compiler that the program will not return any value. The int main() tells the compiler that the program will return an integer value 

Sub Program: sub program is program, and the control of the program is shifted to the called function whenever they are called from the main or outside the main() function. 

// Documentation

/**                    

 * file: sum.c

 * author: you

 * description: program to find sum.

 */

 

// Link

#include <stdio.h>     

 

// Definition

#define X 20

 

// Global Declaration

int sum(int y);  

 

// Main() Function

int main(void)      

{

  int y = 55;

  printf("Sum: %d", sum(y));

  return 0;

}

 

// Subprogram

int sum(int y)

{

  return y + X;

}

 

Output

Sum: 75