Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!usc!henry.jpl.nasa.gov!elroy.jpl.nasa.gov!cit-vax!wen-king
From: wen-king@cit-vax.Caltech.Edu (King Su)
Newsgroups: comp.lang.c
Subject: Re: powerful expressions
Message-ID: <12901@cit-vax.Caltech.Edu>
Date: 8 Dec 89 05:00:34 GMT
References: <12855@cit-vax.Caltech.Edu> <24735@cup.portal.com>
Reply-To: wen-king@cit-vax.UUCP (Wen-King Su)
Distribution: usa
Organization: California Institute of Technology
Lines: 34

In article <24735@cup.portal.com> Tim_N_Roberts@cup.portal.com writes:
>In <12855@cit-vax.Caltech.Edu>, wen-king@cit-vax.Caltech.Edu (King Su)
<shares:
>
<>	((qhead) ? (qtail = qtail->next = qnew)
>>		 : (qtail = qhead       = qnew))->next = 0;
<
>I am truly sorry for the order-of-evaluation flood that I am surely about
<to bring down upon myself, but...
>
<Is this guaranteed to work?

Yes.

Since the posting of the article, I have received exactly two replies.
One contains a better way to do the same thing:

    From: eggert@burns.twinsun.com (Paul Eggert)

		struct QUEUE *qhead = 0, **qtail = &qhead, *qnew;

	To append:

		*(qtail = &(*qtail=qnew)->next) = 0;

The other is a mild criticism.  To which my answer is that I now tend
use such expressions only in macros.  I used to put them in the program
body, but I have been doing less of that because it sometimes happens
that, as I was going through my old programs, I became totally
flabbergasted by some of the stuff I wrote.
-- 
/*------------------------------------------------------------------------*\
| Wen-King Su  wen-king@vlsi.caltech.edu  Caltech Corp of Cosmic Engineers |
\*------------------------------------------------------------------------*/