A function returning the area and perimeter of a circle.

#include <stdio.h>

#define PI 3.142857

void cAreaPeri(float, float *, float *);

int main(void)
{
float radius, area, peri;

printf("\nEnter the radius : ");
scanf("%f", &radius);

cAreaPeri(radius, &area, &peri);

printf("\nArea is %f\nPerimeter is %f", area, peri);

return 0;
}

void cAreaPeri(float r, float *ap, float *pp)
{
*ap = PI * r * r;
*pp = 2 * PI * r;
}