How to find the Area and Circumference of the Circle in C?

In this C Programming example, we will implement the program to find the area and circumference of the circle and print the output on the console.

1. How to find the area and circumference of the circle?

Circumference of the circle is the measurement of the edge of the circle. Whereas the area of the circle represents the region occupied by it.

To determine area and circumference we need to identify the radius of the circle. So, the program will indicate the user to enter the radius. Based on the input it would determine the values.

To make it easier we have taken the standard PI value as 3.14 (constant) in the program.

1.1. What is the formula for the Area of a Circle?

Given that we know the radius the area of circle is calculated as-

A= πr2
Area of a circle

1.2. What is the formula for the Circumference of a Circle?

Given that we know the radius the circumference of the circle is calculated as-

C = 2πr
circumference of a circle
circumference of a circle

So let’s see how it to calculate area and circumference of a circle mathematically.

Example
Input:
radius: 5

Output: 
The Area of circle is:
= 3.14 * 5 * 5
= 78.500000

The Circumference of circle is: 
= 3.14 * 5 * 5
= 31.400002

Helpful topics to understand this program better are-


2. C Program to find the area and circumference of the circle

Let’s discuss the execution(kind of pseudocode) for the program to find the area and circumference of the circle in C.

  1. Initially, we ask the user to enter the radius of the circle.
  2. The input gets stored in the int radius, and the value of the PI, area, and circumference gets stored in the float PI = 3.14, area, circumference respectively.
  3. Now, we perform the calculations on the input to get the area and circumference of the circle using the specified formula.
  4. After the calculations, print the results on the console.

Let us now implement the above execution of the program to find the area and circumference of the circle in C.

#include <stdio.h>
int main() {
  int radius;
  float PI = 3.14, area, circumference;

  printf("Enter the radius of circle: ");
  scanf("%d", &radius);

  area = PI * radius * radius;
  printf("The Area of circle is: %f", area);

  circumference = 2 * PI * radius;
  printf("\nThe Circumference of circle is: %f", circumference);
  return 0;
}
Output
Enter the radius of circle: 2

The Area of circle is: 12.560000
The Circumference of circle is: 12.560000

3. Conclusion

In this C Programming example, we have discussed how to find the area and circumference of the circle in C.


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Happy coding!! 😊

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