define_macro_1.c

#include <stdio.h>
#include <cs50.h>

#define PI 3.14 // declaring what is known as a macro or macro definition

int main(void) {
  
  float circumference, radius;
  
  do
  {
    circumference = get_float("Find the radius of a circle by entering it's circumference: ");
  }
  while(circumference <= 0);
  
  radius = circumference / (2 * PI);

  printf("Radius is equal to %.2f\n",radius);
  
  return 0;
}