# C Programs to Find the Area of a Circle

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:

1. START PROGRAM.
2. TAKE RADIUS AS INPUT FROM USER.
4. PRINT “AREA OF CIRCLE = “
5. END PROGRAM.

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

```#include<stdio.h>
int main()
{
int r;
float area;
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;
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;
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```

Categories C