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From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: quiz for Sequential_IO Read
Date: Sun, 3 Sep 2017 15:44:53 +0200
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Date: 2017-09-03T15:44:53+02:00
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On 09/03/2017 02:47 PM, Frank Buss wrote:
> 
> Why is it a signed type? The range says only 0..255, and in fact, I can write this:
> 
> type Byte is range 0..255; for Byte'Size use 8;
> 
> and it works as expected.

It's signed because the language definition says it's signed. All types declared 
with range are signed. See ARM 3.5.4

http://www.ada-auth.org/standards/rm12_w_tc1/html/RM-3-5-4.html

for the gory details.

If you don't specify 'Size, then the compiler uses the 'Size for the base type. 
If you specify the size it will use that instead. Realistically, stand-alone 
objects will always use complete bytes to store a value, and Sequential_IO will 
read and write that number of bytes. So without a Size clause, Sequential_IO 
read 2 bytes, and with it, only 1.

-- 
Jeff Carter
"Oh Lord, bless this thy hand grenade, that with it thou
mayst blow thine enemies to tiny bits, in thy mercy."
Monty Python and the Holy Grail
24