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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.unix.wizards
Subject: Re: Why doesn't this qsort example work?
Message-ID: <6587@brl-smoke.ARPA>
Date: Mon, 19-Oct-87 09:51:48 EDT
Article-I.D.: brl-smok.6587
Posted: Mon Oct 19 09:51:48 1987
Date-Received: Tue, 20-Oct-87 02:33:02 EDT
References: <7527@g.ms.uky.edu>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 26

In article <7527@g.ms.uky.edu> sean@ms.uky.edu (Sean Casey) writes:
!struct tstr {
!	int a;
!	int b;
!};
!compar(x, y)
!struct tstr *x, *y;
	char *X, *Y;			/* replaces the above line */
!{
	struct tstr *x = X, *y = Y;	/* inserted new line */
!	if (x->a < y->a)	/* coredumps here, therefore a or b is bogus */
!		return(-1);	/* a < b */
!	if (x->a > y->a)
!		return(1);	/* a > b */
!	return(0);		/* a = b */
!}
!main()
!{
!	struct tstr t[2];
!	t[0].a = 1;
!	t[1].a = 2;
!	/* this sorts t[] by the "a" field */
!	qsort(&t[0], 2, sizeof(struct tstr), (*compar)());
	/* replace the above line with the following: */
	qsort((char *)&t[0], (unsigned)2, sizeof(struct tstr), compar);
!}