qsort problem

I called qsort (from standard library) somewhere in my function.

qsort(temp, tree_num, sizeof(int), compare);

I defined compare before the caller in the same .c file.

int compare(const int *a, const int *b)
{
  int val1, val2;

  val1 = *a;
  val2 = *b;

  return (val1 > val2) ? -1 : ((val1 < val2) ? 1 : 0);
}


When compiling, I got this warning:

passing arg 4 of `qsort' from incompatible pointer type

I really could not find out why compare is incompatible.