Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!thetone!swilson
From: swilson%thetone@Sun.COM (Scott Wilson)
Newsgroups: comp.lang.c
Subject: Re: array[-1] -- permitted?
Message-ID: <69575@sun.uucp>
Date: 22 Sep 88 16:15:10 GMT
References: <867@osupyr.mast.ohio-state.edu> <3200@geac.UUCP> <1430@ficc.uu.net> <1988Sep19.164701.11136@ateng.uucp> <2583@ingr.UUCP> <1237@imagine.PAWL.RPI.EDU>
Sender: news@sun.uucp
Reply-To: swilson@sun.UUCP (Scott Wilson)
Organization: Sun Microsystems, Mountain View
Lines: 18

I'm not quite sure what is being discussed.  I assume the standard
says that the -1'th element on an array is not guaranteed to be
accessible, not that negative array indices are disallowed.  For
example, this is legal is it not:

	int array[10], *ip = array;

	ip++;
	foo(ip[-1]);

I assume when yacc uses array index of -1 it is doing something
similar.


--
Scott Wilson		arpa: swilson@sun.com
Sun Microsystems	uucp: ...!sun!swilson
Mt. View, CA