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From: "Jeffrey R. Carter" <jrcarter@acm.org>
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Newsgroups: comp.lang.ada
Subject: Re: Unsigned Integer Restraint Errors
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Date: 2007-03-13T03:13:37+00:00
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Randy Brukardt wrote:
> 
> Ada has signed, checked integers, and unsigned, unchecked integers. It
> doesn't have unsigned, checked integers. That omission is only a problem if
> you need checked, maximum range unsigned integers; usually, you should just
> use an appropriate signed integer type:

 From one point of view, Ada has signed, checked integers:

type Signed_Checked_Byte is range -128 .. 127;

unsigned, checked integers:

type Unsigned_Checked_Byte is range 0 .. 255;
for Unsigned_Checked_Byte'Size use 8;

(with the limitation that the upper bound can't exceed System.Max_Int, 
which is generally < System.Max_Binary_Modulus - 1);

signed, unchecked integers:

type Signed_Unchecked_Byte is range -128 .. 127;
pragma Suppress (Overflow_Check, On => Signed_Unchecked_Byte);

and unsigned, unchecked integers:

type Unsigned_Unchecked_Byte is mod 256;

It seems odd that we use a different syntax for 1 of the 4 (yes, I 
understand that the implications of modular types go beyond the lack of 
overflow checks).

-- 
Jeff Carter
"That was the most fun I've ever had without laughing."
Annie Hall
43