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From: glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups: comp.lang.c,comp.lang.ada,comp.lang.fortran
Subject: Re: condition true or false? ->  (-1 < sizeof("test"))
Date: Tue, 22 May 2012 01:45:10 +0000 (UTC)
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Date: 2012-05-22T01:45:10+00:00
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In comp.lang.fortran Nomen Nescio <nobody@dizum.com> wrote:
(snip) 
>> > >     Negation of unsigned 1 (which can be written `-1u') is already
>> > > defined in C, although there are implementation-defined aspects.
>> > > In particular, there are no "overflow issues," usual or otherwise.

Note that in C this is applying the unary - operator to the
constant 1u. 

In Fortran, except in rare cases (the DATA statement being one)
constants are not signed. (The implentation may apply the unary
minus operator before generating the in-memory constant.)

I would usually write ~0u instead of -1u, but the result is
the same in both cases. 

In Fortran, one could write NOT(0), with the usual restriction
on the bitwise operators on values with the sign bit set.
(In addition to the fact that Fortran doesn't require a binary
representation for data.)

I don't know how ADA treats signed values, or how its bitwise
operators work. This is still posted to the ADA group, though.

-- glen