Constants in C - Explained for Beginners

Introduction

In C programming, constants are values that cannot be changed during the execution of a program. They are used to represent fixed or unchanging values. Understanding constants is essential for writing programs that involve fixed values or settings. In this tutorial, we will explore constants in C and how to use them effectively.

Types of Constants

C supports different types of constants:

• Integer Constants: Represent whole numbers, e.g.,

  42

• Real Constants: Represent real numbers (floating-point), e.g.,

  3.14

• Character Constants: Represent single characters, enclosed in single quotes, e.g.,

  'A'

• String Constants: Represent sequences of characters, enclosed in double quotes, e.g.,

  "Hello, World!"

• Enumeration Constants: User-defined constants, part of an enumeration, e.g.,

  enum Days { MON, TUE, WED };

• Symbolic Constants: Named constants defined using the

  #define

  preprocessor directive, e.g.,

  #define PI 3.14

Using Constants

Constants are used in C to make programs more readable, maintainable, and flexible. They can be used in various ways:

#include <stdio.h>
#define PI 3.14
int main() {
    const int hoursInDay = 24;
    float radius = 5.0;
    float area = PI * radius * radius;
    printf("There are %d hours in a day.\\n", hoursInDay);
    printf("The area of a circle with radius %.2f is %.2f.\\n", radius, area);
    return 0;
}
    

In this example, we use symbolic constants (

PI

#define

hoursInDay

const

Conclusion

Constants play a vital role in C programming by allowing you to represent fixed values clearly and maintainable. You've learned about various types of constants, including symbolic constants, and how to use them in your C programs. As you continue your journey, you'll find constants to be a valuable tool in your coding projects.