Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!pacbell.com!att!cbnewsh!rkl
From: rkl@cbnewsh.att.com (kevin.laux)
Newsgroups: comp.lang.c
Subject: Re: Compound Assignments
Message-ID: <1991Apr16.125259.9072@cbnewsh.att.com>
Date: 16 Apr 91 12:52:59 GMT
References: <1991Apr8.174951.22448@mccc.edu> <15776@smoke.brl.mil> <15823@smoke.brl.mil>
Distribution: na
Organization: AT&T Bell Laboratories
Lines: 32

In article <15823@smoke.brl.mil>, gwyn@smoke.brl.mil (Doug Gwyn) writes:
> In article <1991Apr11.183942.2195@mccc.edu> pjh@mccc.edu (Pete Holsberg) writes:
> >In article <15776@smoke.brl.mil> gwyn@smoke.brl.mil (Doug Gwyn) writes:
> >=In article <1991Apr8.174951.22448@mccc.edu> pjh@mccc.edu (Pete Holsberg) writes:
> >=>=	A compound assignment of the form E1 op= E2 differs from the
> >=>=	simple assignment expression E1 = E1 op (E2) only in that the
> >=>=	lvalue E1 is evaluated only once.

	[stuff about ambiguity and understanding deleted]

	I think the problem of 'ambiguity' arises from what expressions are
chosen as examples.

	For instance,		(E1 = x)

	x += y		and 	x = x + y

	produce the same result but might cause one to say E1 evaluated only
once?

	Whereas			(E1 = x [i++])

	x [i++] += y	and	x [i++] = x [i++] + y

	do not produce the same result but more clearly illustrates the point
that in compound assignments E1 is evaluated only once.

-- 
________________________________________________________________________________
	R. Kevin Laux				Email: rkl1@hound.att.com
	AT&T Bell Labs				Voice: (908) 949-1160
	Holmdel, NJ 07733			Fax:   (908) 949-0959