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From: "Patrick J. LoPresti" <patl@cag.lcs.mit.edu>
To: linux-kernel@vger.kernel.org
Subject: Re: [IDEA+RFC] Possible solution for min()/max() war
In-Reply-To: <Pine.LNX.4.33.0108292018380.1062-100000@penguin.transmeta.com> <20010830165447Z16272-32385+540@humbolt.nl.linux.org> <m266b51c5c.fsf@barnowl.demon.co.uk>
Date: 30 Aug 2001 18:26:18 -0400
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Graham Murray <graham@barnowl.demon.co.uk> writes:

> Daniel Phillips <phillips@bonn-fries.net> writes:
> 
> > More than anything, it shows that education is needed, not macro patch-ups.
> > We have exactly the same issues with < and >, should we introduce 
> > three-argument macros to replace them?
> 
> Would it not have been much more "obvious" if the rules for
> unsigned/signed integer comparisons (irrespective of the widths
> involved) were
> 
> 1) If the signed element is negative then it is always less than the
>    unsigned element.
> 
> 2) If the unsigned element is greater than then maximum positive value
>    expressible by the signed one then it is always greater.
> 
> 3) Only if both values are positive and within the range of the
>    smaller element are the actual values compared. 

With infinite-precision arithmetic, yes; of course min() should just
return the smaller value.

But what would the C type of "min" be for comparing, say, signed and
unsigned longs?  The range of possible results does not fit in any
integral type.  (Repeat the question for signed/unsigned "long long"
if "long long" is your answer.)

 - Pat