🚀 go-pugleaf

> >             It would surprise me not at all if qsort() relied on
>                                                          ^^^^^^^^^
> > sort_func() having the property that
> 
> >	!!sort_func(p1, p2) == -1 * !!sort_func(p2, p1)
> 
> Of course, in comp.std.c, I should have said "...were permitted to rely on..."

Better yet, you should have not have assumed that !!x would produce -1
when x < 0.  <grin>

Incidentally, I have encountered code where the comparison function for
qsort() actually WAS specified with a return expression like *a < *b that
produced 0 when it should have produced -1.  The interesting part is that,
on the particular machine the programmer had been using, the sort worked
correctly.  Evidently this particular qsort() implementation only tested
whether the comparison function returned a positive value or not.

-- 
Mark Brader, msb@sq.com, SoftQuad Inc., Toronto
        "I'm a little worried about the bug-eater," she said.  "We're embedded
        in bugs, have you noticed?"             -- Niven, "The Integral Trees"

My text in this article is in the public domain.