test for function for counting number of non-zero bits in a 32-bit word

Here's a test for the previous function:

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

uint32_t count_nonzero_bits(uint32_t n)
{
  uint32_t masks[] = { 0x55555555, 0x33333333, 0x0F0F0F0F, 0x00FF00FF, 0x0000FFFF };
  size_t i;
  for(i=0; i < 5; i++)
  {
    n = (n & masks[i]) + ((n >> (1 << i)) & masks[i]);
  }
  return n;
}

uint32_t count_nonzero_bits_slow(uint32_t n)
{
  uint32_t cnt=0;
  uint8_t tmp=0;
  while(n>0) {
    tmp = n&1;
    cnt += tmp;
    n >>= 1;
  }
  return cnt;
}

int main() {
  srand(time(0));
  uint32_t iter, X;
  for (iter=0; iter<1000; iter++) {
    X=rand();
    if (count_nonzero_bits(X)!=count_nonzero_bits_slow(X))
      printf("test failed (number=%u)\n", X);
  }
  printf("tests finished\n");
  return 0;
}

enjoy!