text: /*  Example: C program to find area of a circle */
  
  #include <stdio.h>
  #define PI 3.14159
  
  int main()
  {
    float r, a, c;
  
    printf("Enter radius (in mm):\n");
    scanf("%f", &r);
  
    while (r != 0) {
    r /= 25.4;
    a = PI * r * r;
    c = PI * r * 2;
  
    printf("Circle's area is %3.2f (sq in).\n", a);
    printf("Its circumference is %3.2f (in).\n", c);
  
    printf("Enter radius (in mm):\n");
    scanf("%f", &r);
    }
    printf("Exit\n");
  }
  