From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM,XPRIO
	autolearn=ham autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,32c6d2fb891775fc,start
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2003-10-28 04:13:13 PST
Path: 
 archiver1.google.com!news2.google.com!news.maxwell.syr.edu!newsfeed00.sul.t-online.de!newsmm00.sul.t-online.com!t-online.de!news.t-online.com!not-for-mail
From: "Lars" <lars-remove_me-m@gmx.net>
Newsgroups: comp.lang.ada
Subject: Modular integers
Date: Tue, 28 Oct 2003 13:13:28 +0100
Organization: T-Online
Message-ID: <bnlmg1$kqv$04$1@news.t-online.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit
X-Trace: news.t-online.com 1067343169 04 21343 NrpNVf1VSmHNVz 031028 12:12:49
X-Complaints-To: usenet-abuse@t-online.de
X-ID: SPeJrrZHgeK2fj6Y00CFqmLZoYyrgp2TiOwLgx5FAEZDJpevjauYZR
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2800.1158
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165
Xref: archiver1.google.com comp.lang.ada:1766
Date: 2003-10-28T13:13:28+01:00
List-Id: <comp.lang.ada>

Hi,

I was able to create an unsigned 64-bit integer using

    type unsigned_64_bit_integer is mod 2**64;

Then I defined a subtype:

    subtype safe_unsigned_64_bit_integer is unsigned_64_bit_integer range 0
.. 2**64-1;

When a variable of type unsigned_64_bit_integer contains 2**64-1 and you add
1, it is "reset" to 0, as expected.
When a variable of type safe_unsigned_64_bit_integer contains 2**64-1 and
you add 1, no exception is raised and it is "reset" to 0.

Why is that? Shouldn't the compiler be able to insert a check that throws an
exception if an overflow occurs?

-Lars