A C program follows a standard structure that makes it organized, readable, and easy to maintain.

1. Documentation Section

• Contains comments describing the program.
• Explains the purpose, author, and date.

Example:

/* Program to print Hello, World! */

2. Link Section

• Includes the required header files using the #include directive.

Example:

#include <stdio.h>

3. Definition Section

• Defines symbolic constants using the #define directive.

Example:

#define PI 3.14159

4. Global Declaration Section

• Declares global variables and function prototypes.
• These can be accessed throughout the program.

Example:

int total;
void display();

5. Main() Function

• The execution of every C program starts from the main() function.
• It contains declarations, executable statements, and a return statement.

Example:

int main()
{
    printf("Hello, World!\n");
    return 0;
}

6. User-Defined Functions

• Functions written by the programmer to perform specific tasks.
• These are called from the main() function.

Example:

void display()
{
    printf("Welcome to C Programming");
}

Complete Example

/* Program to Demonstrate Structure of a C Program */

#include <stdio.h>

#define PI 3.14159

void display();

int main()
{
    printf("This is the main function.\n");
    display();
    return 0;
}

void display()
{
    printf("Welcome to C Programming.\n");
}

Output

This is the main function.
Welcome to C Programming.

Summary