Radix Conversion from Ruby

#include <stdio.h>
#include <stdlib.h>

const char digitmap[] = "0123456789abcdef";

char *num_to_s(int val, int base) {
  char *ret = (char *)malloc(sizeof(char) * 255);
  ret = ret + 255;
  *--ret = '\0';
  do {
    *--ret = digitmap[(int )(val % base)];
  } while (val /= base);
  return ret;
}

int main(int argc, char **argv) {
  int n = 1424;
  printf("base 2: %s\n", num_to_s(n, 2));
  printf("base 4: %s\n", num_to_s(n, 4));
  printf("base 8: %s\n", num_to_s(n, 8));
  printf("base 16: %s\n", num_to_s(n, 16));
  return EXIT_SUCCESS;
}