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From: "Martin Dowie" <martin.dowie@gecm.com>
Subject: constants v variables (was Re: if statements)
Date: 2000/11/09
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Date: 2000-11-09T00:00:00+00:00
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Robert Dewar <robert_dewar@my-deja.com> wrote in message
news:8udce8$1qi$1@nnrp1.deja.com...
[snip]
> Fifth, Temp is a variable, when it should be a constant. People
> very much overuse variables.

Thanks for highlighting this one - I've been bleeting on about this locally
(and even in c.l.a. once!) for ages to collegues. I've noticed that apart
from the analysis-of-the-problem meaning (i.e. it shows that the value has
been determined to be the same thoughout its scope) there are also
efficiency benefits, at least on one of our target compilers (in
non-optimising mode, untried when optimising).

My question is - can these efficiencies be expected from a compiler, by the
way the ARM defines variables v constants, or is this just because of the
particular compiler we were using. Will any 'decent' compiler spot when a
'variable' should actually have been declared as a constant?