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From: "BartC" <bc@freeuk.com>
Newsgroups: comp.lang.c,comp.lang.ada,comp.lang.fortran
Subject: Re: condition true or false? ->  (-1 < sizeof("test"))
Date: Tue, 22 May 2012 10:55:01 +0100
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Date: 2012-05-22T10:55:01+01:00
List-Id: <comp.lang.ada>

"Nomen Nescio" <nobody@dizum.com> wrote in message
news:eb42d1e8b4d1e87bc804d05ec6964bc3@dizum.com...
> glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:

>> I don't know how ADA treats signed values, or how its bitwise
>> operators work. This is still posted to the ADA group, though.
>
> I'm not an expert on this but Ada is very strongly (statically) typed.
> There
> are only two integer types in Ada to start with, signed integer and
> modular
> integer. The compiler will flag an error if you try to compare variables
> of
> those two types or indeed variables of any differing types.

Signed and modular is a better way of explaining how C treats these types,
with a clear distinction between them.

Signed types clearly should be the primary way to represent actual integer
quantities as most of us think of them. A signed integer range can represent
any positive value (given enough bits); an unsigned range can't represent
any positive or  negative value (not with a finite number of bits anyway).

That's why it's odd that when there is any hint of a unsigned operand, C
should switch to modular arithmetic for both.

But, given that C works at a lower level, and the choice of bit-widths is
limited, then perhaps there ought to be 3 integer types:

- Signed
- New-unsigned
- Modular

With the new-unsigned type behaving as I have suggested a few times [in the
original thread in comp.lang.c], just a subrange of a signed type (for
example, a hypothetical signed integer type that is one bit wider).

With the new-unsigned type, a negation operation must have signed result
(because, other than -0, it will be negative). While subtraction would need
to be signed too, as results can be negative. And of course there is the 
likelihood of overflow or underflow, for which I will leave to other 
language proposals to deal with..

-- 
Bartc