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From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Compound Assignments
Message-ID: <15776@smoke.brl.mil>
Date: 10 Apr 91 04:14:27 GMT
References: <1991Apr4.205257.15205@mccc.edu> <1991Apr6.195901.25255@dvorak.amd.com> <1991Apr8.174951.22448@mccc.edu>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 14

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.
>The reference to E1 is ambiguous, as is the entire statement, IMHO. 
>*Which* E1 is evaluated "only once", the E1 op= E2 one or the other? 
>Does it follow that the remaining one is evaluated twice?  not at all?

You have GOT to be kidding -- there is nothing at all ambiguous about
the quoted specification.  It is an elegant way of expressing precisely
the semantics for op=.  I suggest you study it until enlightenment
suddenly dawns upon you.

Wu.