C Program to Find Diameter, Circumference, and Area of a Circle

In this tutorial, i am going to show you how to find or calculate the diameter, circumference and area of a circle using the formula, function, and math modules in c programs.

All C Programs and Algorithm to Find the Area of a Circle

• Algorithm To Find Diameter, Circumference, and Area of a Circle
• C Program to Find Diameter, Circumference, and Area of a Circle using Formula
• C Program to Find Diameter, Circumference, and Area of a Circle using Function
• C Program to Find Diameter, Circumference, and Area of a Circle using Math Module

Algorithm To Find Diameter, Circumference, and Area of a Circle

Follow the below given algorithm to write a program to find diameter, circumference and area of a circle; as follows:

1. START PROGRAM.
2. TAKE RADIUS AS INPUT FROM USER.
3. FIND AREA OF DIAMETER, CIRCUMFERENCE, CIRLCE USING THE FOLLOWING FORMULAS:
   1. diameter = 2 * radius;
   2. circumference = 2 * PI * radius;
   3. area = PI * radius * radius;
4. PRINT “AREA OF CIRCLE, DIAMETER, CIRCUMFERENCE “
5. END PROGRAM.

C Program to Find Diameter, Circumference, and Area of a Circle using Formula

/* C Program to find Diameter, Circumference, and Area Of a Circle */
 
#include<stdio.h>
 
#define PI 3.14
 
int main()
{
  float radius, area, circumference, diameter;
 
  printf("\n Please Enter the radius of a circle : ");
  scanf("%f",&radius);
 
  diameter = 2 * radius;
  circumference = 2 * PI * radius;
  area = PI * radius * radius; 
 
  printf("\n Diameter Of a Circle = %.2f\n", diameter);
  printf("\n Circumference Of a Circle = %.2f\n", circumference);
  printf("\n Area Of a Circle = %.2f\n", area);
 
  return 0;
}

The result of the above c program; as follows:

Please Enter the radius of a circle : 5
Diameter Of a Circle = 10.00

 Circumference Of a Circle = 31.40

 Area Of a Circle = 78.50

C Program to Find Diameter, Circumference, and Area of a Circle using Function

/* C Program to find Diameter, Circumference, and Area Of a Circle */
#include<stdio.h>
#include<math.h>
double find_Diameter(double radius);
double find_Circumference(double radius);
double find_Area(double radius);
int main()
{
  float radius, area, circumference, diameter;
 
  printf("\n Please Enter the radius of a circle : ");
  scanf("%f",&radius);
 
  diameter = find_Diameter(radius);
  circumference = find_Circumference(radius);
  area = find_Area(radius); 
 
  printf("\n Diameter Of a Circle = %.2f\n", diameter);
  printf(" Circumference Of a Circle = %.2f\n", circumference);
  printf(" Area Of a Circle = %.2f\n", area);
 
  return 0;
}
double find_Diameter(double radius)
{
   return 2 * radius;
}
double find_Circumference(double radius)
{
   return 2* M_PI * radius;
}
double find_Area(double radius)
{
   return M_PI * radius * radius;
}

The result of the above c program; as follows:

Please Enter the radius of a circle : 5
Diameter Of a Circle = 10.00
 Circumference Of a Circle = 31.42
 Area Of a Circle = 78.54

C Program to Find Diameter, Circumference, and Area of a Circle using Math Module

/**
 * C program to calculate diameter, circumference and area of circle
 */
#include <stdio.h>
#include <math.h> // Used for M_PI
int main()
{
    float radius, diameter, circumference, area;
    
    /*
     * Input radius of circle from user
     */
    printf("Enter radius of circle: ");
    scanf("%f", &radius);
    /*
     * Calculate diameter, circumference and area of circle
     */
    diameter = 2 * radius;
    circumference = 2 * M_PI * radius;
    area = M_PI * (radius * radius);
    /*
     * Print all results
     */
    printf("Diameter of circle = %.2f units \n", diameter);
    printf("Circumference of circle = %.2f units \n", circumference);
    printf("Area of circle = %.2f sq. units ", area);
    return 0;
}

The result of the above c program; as follows:

Enter radius of circle: 10
Diameter of circle = 20.00 units 
Circumference of circle = 62.83 units 
Area of circle = 314.16 sq. units 

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