Structure of a C Program

Introduction

• Overview of the basic structure of a C program.
• Discussion of sections in a C program.
• Some sections are optional, while others are essential.

1. Documentation Section (Comment Section)

• Purpose: Provides information about the program.
• Includes:
  • Author's name (e.g., Jayanti Khatri)
  • Date and time of development
  • Brief description of the program (e.g., "Program for addition of two numbers")
• Comments:
  • Single-line comments: // (e.g., // Program for addition of two numbers)
  • Multi-line comments: /* ... */
• Importance:
  • Helps future users understand the code.

2. Link Section

• Includes header files necessary for the program.
• Example:
  • #include <stdio.h> (Standard Input Output Library)
• Purpose of header files:
  • To provide definitions for built-in functions like printf and scanf.
• Other common header files:
  • #include <conio.h> (for console input/output)
  • #include <math.h> (for math functions)
  • #include <string.h> (for string functions)
• Importance:
  • The linker integrates these functions into the program.

3. Definition Section

• Defines symbolic constants using #define.
• Example:
  • #define PI 3.14
  • Use of macros to simplify code and make it easier to update.

4. Global Declaration Section

• Declaration of global variables and user-defined functions.
• Global variables can be accessed by all functions in the program.
• Local variables are accessible only within the function they are declared in.
• Example:
  • int a; (global declaration)

5. Main Section

• Essential and must be included in every C program.
• Only one main function is allowed per program.
• Structure:
  • void main() {}
  • Two parts:
    • Declaration part (optional)
    • Executable part (must contain at least one statement)
• Example:
  • printf(