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Path: utzoo!linus!decvax!harpo!seismo!hao!hplabs!sdcrdcf!randvax!edhall
From: edhall@randvax.ARPA (Ed Hall)
Newsgroups: net.lang.c
Subject: Re: integer *= float
Message-ID: <1612@randvax.ARPA>
Date: Thu, 5-Jan-84 22:38:13 EST
Article-I.D.: randvax.1612
Posted: Thu Jan  5 22:38:13 1984
Date-Received: Sun, 8-Jan-84 04:47:01 EST
References: <4759@decwrl.UUCP>
Organization: Rand Corp., Santa Monica
Lines: 22

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We have tried  integer *= float  with 5 different C compilers, and all
of them convert the float before the multiplication:
	1) PCC on the VAX,
	2) CC on the PDP-11 (i.e., the Ritchie compiler),
	3) the UniSoft C compiler on the CYB,
	4) AZTEC C on the APPLE,
	5) C-86 on the IBM PC (Computer Innovations).

I've seen at least two cases where code was broken due to this
counter-intuitive behavior.  A `fix' to PCC is not particularly
difficult (at least for the VAX); I have one, but won't post it
until this question is settled.

Thus, the VMS C compiler seems to be in the minority.  If the Ritchie
compiler is considered to be the `reference', then it would seem
that C does the counter-intuitive thing.  But reading the appropriate
part of K&R numerous times leaves me with the clear impression that the
conversion belongs after the operation and before the store.

		-Ed Hall
		decvax!randvax!edhall