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From: torek@elf.ee.lbl.gov (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: Assignment Ops and Side Effects
Message-ID: <11805@dog.ee.lbl.gov>
Date: 4 Apr 91 22:17:48 GMT
References: <1991Apr3.173046.2367@mccc.edu> <1991Apr4.202314.961@csrd.uiuc.edu>
Reply-To: torek@elf.ee.lbl.gov (Chris Torek)
Organization: Lawrence Berkeley Laboratory, Berkeley
Lines: 26
X-Local-Date: Thu, 4 Apr 91 14:17:48 PST

In article <1991Apr4.202314.961@csrd.uiuc.edu> bliss@sp64.csrd.uiuc.edu
(Brian Bliss) notes that on at least one system:
>	char ch;
>	sizeof (ch += 1) == 4
>	sizeof (ch++) == 1
>apparrently operands of ++ and -- do not undergo integral promotion

I am tempted to claim that this is a bug in the compiler in question,
but without the standard in front of me (I am reading news during
breakfast at home) I will go only as far as saying that, from a
reasonably abstract point of view,

	ch++

and

	ch += 1

should have the same type.  Gcc 1.39, for instance, makes them the same.
I doubt that gcc violates the standard in this regard, so either it is
undefined or implementation-defined as to exactly when promotion occurs
in assignment expressions, or else the compiler that gave you that
result is not conformant.
-- 
In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE (+1 415 486 5427)
Berkeley, CA		Domain:	torek@ee.lbl.gov