Write a temp conversion program that uses a function

#include <stdio.h>
float celsius(float fahr);
  
/*print Fahrenheit - Celsius table
  for fahr = 0, 20, ......., 300; floating-point version 
   */
int main(){
    float fahr;
    int lower, upper, step;

    lower =0;          /*lower limit of temperature */
    upper = 300;       /*upper limit */
    step = 20;          /*step size */

    fahr = lower;
    while (fahr <= upper){
          printf("%3.0f %6.1f\n", fahr, celsius(fahr));
          fahr = fahr + step;
    }
}
/*celsius: convert fahr into celsius    */
float celsius(float fahr){
      return (5.0 / 9.0) * (fahr - 32.0);
}