[zokier]

    #include<stdio.h>

    int main(void) {
      long a = (float)9999999999999999;
      long b = 9999999999999998;
      printf("%ld - %ld = %ld\n", a, b, a-b);
    }

produces

    10000000272564224 - 9999999999999998 = 272564226