Path: utzoo!attcan!uunet!husc6!bloom-beacon!tut.cis.ohio-state.edu!mailrus!wasatch!utah-gr!uplherc!sp7040!obie!wsccs!terry
From: terry@wsccs.UUCP (Every system needs one)
Newsgroups: comp.lang.c
Subject: Re: array[-1] -- permitted?
Message-ID: <680@wsccs.UUCP>
Date: 28 Sep 88 04:27:41 GMT
References: <867@osupyr.mast.ohio-state.edu> <3200@geac.UUCP> <1430@ficc.uu.net> <1237@imagine.PAWL.RPI.EDU>
Lines: 36

In article <1237@imagine.PAWL.RPI.EDU>, kyriazis@rpics (George Kyriazis) writes:
> Excuse for the question, but that is the first time I am looking at that
> subject and I don't see any reason why x[-a] can't be permitted, mainly
> for two basic reasons:
>     (a)	x[a] == *(x+a)  therefore  x[-1] == *(x-1), which looks
> 	perfectly ok to me.
> 
>     (b)	yacc uses array[-1].  If it is considered invalid, that will mean
> 	that yacc has to be rewriten for the new standard?
> 
> Am I missing something?

Yes.

The source for who contains the following type of thing:

char *str = "hello world"+6;

where 	printf( "'%c'", str[ -6]);

gives	'h'.

This is is used in the "who am i" command.

It works on most C compilers (with 1 exception still in developement).  The
exception is due to the method of compilation requiring a "fake node" to
make it work.  DMR is quoted as saying it should work by the compiler writer,
even in ANSI C.


| Terry Lambert           UUCP: ...{ decvax, ihnp4 } ...utah-cs!century!terry |
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