Fahrenheit/Celsius table

main.c

#include <stdio.h>

#define LOWER 0   /* lower limit of temp. table (in Fahrenheit) */
#define UPPER 300 /* upper limit */
#define STEP 20   /* step size */

double fahrenheitToCelsius(int fahr) {
  return (5.0 / 9.0) * (fahr - 32.0);
}

void printConversion(int fahr) {
  printf("%3d \t %6.1f\n", fahr, fahrenheitToCelsius(fahr));
}

void printConversions(int fahr) {
  if (fahr > UPPER) {
    return;
  } else {
    printConversion(fahr);
    return printConversions(fahr + STEP);
  }
}

int main(void) {
  printConversions(LOWER);
}

output

  0 	  -17.8
 20 	   -6.7
 40 	    4.4
 60 	   15.6
 80 	   26.7
100 	   37.8
120 	   48.9
140 	   60.0
160 	   71.1
180 	   82.2
200 	   93.3
220 	  104.4
240 	  115.6
260 	  126.7
280 	  137.8
300 	  148.9