strqueue_diff(Strqueue *sq1, Strqueue *sq2, Strqueue *osq)
{
  int i = 0, j = 0;
  while (i < sq1->nstr && j < sq2->nstr)
    {
      int r = strqueue_sort_cmp(sq1->str + i, sq2->str + j, 0);
      if (!r)
	i++, j++;
      else if (r < 0)
	strqueue_pushjoin(osq, "-", sq1->str[i++], 0);
      else
	strqueue_pushjoin(osq, "+", sq2->str[j++], 0);
    }
  while (i < sq1->nstr)
    strqueue_pushjoin(osq, "-", sq1->str[i++], 0);
  while (j < sq2->nstr)
    strqueue_pushjoin(osq, "+", sq2->str[j++], 0);
}
strqueue_diff(Strqueue *sq1, Strqueue *sq2, Strqueue *osq)
{
  int i = 0, j = 0;
  while (i < sq1->nstr && j < sq2->nstr)
    {
      int r = strqueue_sort_cmp(sq1->str + i, sq2->str + j, 0);
      if (!r)
	i++, j++;
      else if (r < 0)
	strqueue_pushjoin(osq, "-", sq1->str[i++], 0);
      else
	strqueue_pushjoin(osq, "+", sq2->str[j++], 0);
    }
  while (i < sq1->nstr)
    strqueue_pushjoin(osq, "-", sq1->str[i++], 0);
  while (j < sq2->nstr)
    strqueue_pushjoin(osq, "+", sq2->str[j++], 0);
}