Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: comma operator
Message-ID: <7082@brl-smoke.ARPA>
Date: 14 Jan 88 10:21:44 GMT
References: <3819@sigi.Colorado.EDU>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 21

In article <3819@sigi.Colorado.EDU> swarbric@tramp.Colorado.EDU (SWARBRICK FRANCIS JOHN) writes:
>So, what is the advantage of using the comma operator other than to squeeze
>everything on to one line?

There are two primary legitimate uses for the comma (sequencing) operator,
typified by:

	for ( i = n, p = array; *p != 0; --i, ++p )
		;

where the comma operator permits multiple operations in each part of the
for(), and

	#ifndef lint
	#define	MmAllo( t )	((t *)Mm_QAllo( sizeof(t) ))
	#else
	#define	MmAllo( t )	((void)Mm_QAllo( sizeof(t) ), (t *)0)
	#endif

where the comma operator permits multiple operations in producing a single
value for an expression.