C Program to Find Circumference of Circle

In this tutorial, we are going to write a C program that calculates the circumference of a circle.

Formula for Circumference of a Circle

The circumference of a Circle is the total length around its boundary. It is calculated by using the formula

Circumference = 2*π*r

Where

• π is a mathematical constant approximately equal to 3.14159
• r is the radius of the circle.

C Program for Circumference of Circle

#include <stdio.h>
#define PI 3.14159 // Defining the value of Pi
float calculateCircumference(float radius)
{
    return 2 * PI * radius;
}
void main()
{
    float radius;
    printf("Enter the radius");
    scanf("%f", &radius);
    if (radius < 0)
    {
        printf("Radius cannot be zero");
    }
    else
    {
        printf("Circumference of given circle = %f", calculateCircumference(radius));
    }
}

Output-

How the Above C Program Work?

• The program starts by asking the user to input the radius of the circle.
• In the program, we define the mathematical constant π by using # to define the preprocessor directive.
• The calculateCircumference function takes the circle’s radius as argumnet and returns the circumference using the abovementioned formula.
• In the main function after taking input from the user it takes if the radius is non-negative.
• Finally, the program calculates and displays the circumference of the circle based on the provided radius.

See Also

• Odd Even in Java
• Fibonacci Series Java