#include <stdio>

main()
{
  int fahr, celsius;
  int lower, upper, step;

  lower = 0;
  upper = 300;
  step = 20;

  fahr = lower;
  while (fahr <= upper)
  {
    celsius = 5 * (fahr - 32) / 9;
    printf("%d\t%d\n",fahr, celsius);
    //printf(fahr, celsius);
    fahr = fahr + step;
  }
}

i get error
temperature.c:1:17: error: stdio: No such file or directory
temperature.c: In function ‘main’:
temperature.c:16: warning: incompatible implicit declaration of built-in function ‘printf’