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From: asd@cbnewsj.att.com (Adam S. Denton)
Newsgroups: comp.lang.c
Subject: Re: qsort()
Message-ID: <1991Apr22.174958.15420@cbnewsj.att.com>
Date: 22 Apr 91 17:49:58 GMT
References: <1991Apr22.002627.14535@engin.umich.edu>
Organization: AT&T
Lines: 24

In article <1991Apr22.002627.14535@engin.umich.edu> garath@irie.ais.org (Belgarath) writes:
>qsort((char *) info, 49, sizeof(the_srtuct), compare);
>
>int compare(ptr1, ptr2) 
>struct the_struct *ptr1;
>struct the_struct *ptr2;
>{
>	return (strcmp(ptr1->name, ptr2->name));
>}

Not quite.  This should really be
    int compare(ptr1,ptr2)
         char *ptr1, *ptr2;
    {
         return strcmp( ((struct the_struct *)ptr1)->name,
                        ((struct the_struct *)ptr2)->name );
    }
and in an ANSI environment, "void *" should be used instead of "char *".

qsort() passes generic pointers to compare(), not struct pointers.
There is no guarantee the two pointer types are interchangeable.

Adam Denton
asd@mtqua.att.com