Date: Mon, 16 Sep 2002 11:30:03 -0700 (PDT) From: "Jin Guojun [DSD]" <j_guojun@lbl.gov> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/42818: qsort can only sort up to 6 element for structure Message-ID: <200209161830.g8GIU3YE013033@freefall.freebsd.org>
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The following reply was made to PR kern/42818; it has been noted by GNATS.
From: "Jin Guojun [DSD]" <j_guojun@lbl.gov>
To: Gregory Bond <gnb@itga.com.au>
Cc: FreeBSD-gnats-submit@FreeBSD.ORG
Subject: Re: kern/42818: qsort can only sort up to 6 element for structure
Date: Mon, 16 Sep 2002 11:26:29 -0700
My fault -- I typed a wrong operator "<". It supposes to be "-". So, the correct
operation
is:
int smaller(const void *i1, const void *i2)
{
return *(int*)i1 - *(int*)i2;
}
Thanks,
-Jin
Gregory Bond wrote:
> The bug is in your program. To quote qsort(3):
>
> The comparison function must return an integer less than, equal to, or
> greater than zero if the first argument is considered to be respectively
> less than, equal to, or greater than the second.
>
> Your comparison function returns 0 or 1 only. Perhaps you are being confused
> by the C++/STL comparison objects?
>
> Modifying your comparison fn to the following makes it work:
> int
> smaller(const void *i1, const void *i2)
> {
> if (*(int*)i1 < *(int*)i2) return -1;
> return *(int*)i1 > *(int*)i2;
> }
>
> The fact that your test program seems to work for these test cases on Solaris
> and Linux is a simple coincidence, and depends on fine internal details of the
> sort algorithm on those systems. There will probably be other cases where the
> Linux/Solaris qsort() will also fail.
>
> This PR can be closed.
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