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From: vishniac@wanginst.UUCP (Ephraim Vishniac)
Newsgroups: net.lang.c
Subject: Re: ? : operator in lvalue
Message-ID: <486@wanginst.UUCP>
Date: Wed, 17-Apr-85 13:37:51 EST
Article-I.D.: wanginst.486
Posted: Wed Apr 17 13:37:51 1985
Date-Received: Sat, 20-Apr-85 05:25:08 EST
References: <704@mako.UUCP>
Distribution: net
Organization: Wang Institute, Tyngsboro, Ma.  01879
Lines: 24

> Is it considered kosher to use the ``? :'' operator
> in computing an lvalue, as in
> 
> 	int a, b, c;
> 
> 	*(a ? &b : &c) = 47;
> 
> This is certainly legal C, but I never recall
> seeing it used in any code I have looked at.

Legality may not be enough: some C compilers will choke on it anyway.
I recently discovered that the Mark Williams C compiler (for 8086/8088)
refuses to accept:

	int a[3], b;

	a[ b ? 1 : 2] = 47;

It complains that the stuff on the left of the assignment is not an lvalue.

-- 
Ephraim Vishniac
  [apollo, bbncca, cadmus, decvax, harvard, linus, masscomp]!wanginst!vishniac
  vishniac%Wang-Inst@Csnet-Relay