// Example loop to look at different kinds of loops.

typedef unsigned long size_t;

// Forward.  Returns index past end if not found.
size_t
findnum(int *a, size_t n, int k)
{
  for (size_t i = 0; i != n; i++) {
    if (a[i] == k) return i;
  }

  return n;
}

// Backward.  Finds last occurrence, returns (size_t)-1 on failure.
size_t
findnum_b(int *a, size_t n, int k)
{
  while (n--) {
    if (a[n] == k) break;
  }

  return n;
}

// With sentinel, mutating array, as Knuth recommends in "Structured
// Programming With go to Statements."
size_t
findnum_s(int *a, size_t n, int k)
{
  a[n] = k;
  for (size_t i = 0; ; i++) {
    if (a[i] == k) return i;
  }
}

// With sentinel, mutating array, returning pointer.
int*
findnum_p(int *a, size_t n, int k)
{
  a[n] = k;
  while (*a != k) a++;
  return a;
}