In this tutorial, i am going to show you how to find or calculate the area of a circle with the help of standard formula, function, and poiter in c programs.

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

- Algorithm To Find Area Of a Circle
- C Programs to Find the Area of a Circle using Formula
- C Programs to Find the Area of a Circle using Function
- C Programs to Find the Area of a Circle using Pointer

### Algorithm To Find Area Of a Circle

Use the below given algorithm to write a program to find area of a circle; as follows:

- START PROGRAM.
- TAKE RADIUS AS INPUT FROM USER.
- FIND AREA OF A CIRLCE USING THIS FORMULA AREA=3.14*RADIUS*RADIUS.
- PRINT “AREA OF CIRCLE = “
- END PROGRAM.

### C Programs to Find the Area of a Circle using Formula

#include<stdio.h> int main() { int r; float area; printf("Please enter radius of the circle: "); scanf("%d",&r); area=(22*r*r)/7; printf("The area of circle is: %f\n",area); return 0; }

The output of the above c program; as follows:

Please enter radius of the circle: 15 The area of circle is: 707.000000

### C Programs to Find the Area of a Circle using Function

#include<stdio.h> float area(int r) { return (22*r*r)/7; } int main() { int r; float a; printf("Please enter radius of the circle: "); scanf("%d",&r); a=area(r); printf("area of the circle: %f\n",a); return 0; }

The output of the above c program; as follows:

Please enter radius of the circle: 5 area of the circle: 78.000000

### C Programs to Find the Area of a Circle using Pointer

#include<stdio.h> void area(int *r,float *a) { *a=(22*(*r)*(*r))/7; } int main() { int r; float a=1; printf("Please enter radius of the circle: "); scanf("%d",&r); area(&r,&a); printf("The area of circle is: %f\n",a); return 0; }

The output of the above c program; as follows:

Please enter radius of the circle: 7 The area of circle is: 154.000000