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Article #9605

Re: Portable Languages (was: Expression sequencing query)

#9605
From: Jason Zions
Date: Thu, 16 Oct 1986 17:33
27 lines
1742 bytes
dik@mcvax.uucp (Dik T. Winter) writes:
> And so should it.  Once I required the expression (A - B) - C evaluated
> exactly that way.  It didn't do so.  However, after removing the
> parenthesis it was evaluated the way I wanted.  Counterintuitive?

Not counterintuitive - BROKEN. Although C may rearrange the order of
evaluation with respect to + * & ^ and |, it may not do so w.r.t. operators
which aren't associative and commutative.

Rearranging (A - B) - C is just plain wrong.

References:
H&S Section 7.11, page 190
K&R Section 2.12, page 49

Note that both references state that reordering is permitted only for the
associative and commutative operators; they do not mention the names of the
operators for which reordering is forbidden.
--
This is not an official statement of Hewlett-Packard Corp., and does not 
necessarily reflect the views of HP. It is provided completely without warranty
of any kind. Lawyers take 3d10 damage and roll a saving throw vs. ego attack.

Jason Zions				Hewlett-Packard
Colorado Networks Division		3404 E. Harmony Road
Mail Stop 102				Ft. Collins, CO  80525
	{ihnp4,seismo,hplabs,gatech}!hpfcdc!hpcnoe!jason
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From: jason@hpcnoe.UUCP (Jason Zions)
Newsgroups: net.lang.c
Subject: Re: Portable Languages (was: Expression sequencing query)
Message-ID: <790007@hpcnoe.UUCP>
Date: Thu, 16-Oct-86 13:33:21 EDT
Article-I.D.: hpcnoe.790007
Posted: Thu Oct 16 13:33:21 1986
Date-Received: Tue, 21-Oct-86 21:50:41 EDT
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Organization: HP Colorado Networks Division
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