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
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!.POSTED!not-for-mail
From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.ada
Subject: Re: How to make Ada popular. Get rid of ";" at end of statement.
Date: Fri, 26 Jul 2019 21:06:05 -0700
Organization: None to speak of
Message-ID: <lna7d05dg2.fsf@kst-u.example.com>
References: <qgtdf4$7ej$1@gioia.aioe.org>
	<5d9a8728-3c5b-4caf-b765-a455ba4d3523@googlegroups.com>
	<5fb45b9c-d7da-447c-999e-0e8bcce2eed5@googlegroups.com>
	<1dc13d50-7606-4530-b5cc-19e07b4d4938@googlegroups.com>
	<cd5cf8f4-2c6a-4fd2-a696-9f2a07287b36@googlegroups.com>
	<lnh8785kge.fsf@kst-u.example.com>
	<qhgfd1$h24$1@franka.jacob-sparre.dk>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Injection-Info: reader02.eternal-september.org;
 posting-host="d8a2633722fb5b0a068c2be01b0d1b9e";
	logging-data="32278"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX19nmq7y1EbxfkPSF+NvqZ5a"
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux)
Cancel-Lock: sha1:sH6qjw7yYD4YMQ8+qz3Dvfcd4Ts=
	sha1:NrA6rx3ZK+BI3T3Rn+tRfO9PHT4=
Xref: reader01.eternal-september.org comp.lang.ada:56970
Date: 2019-07-26T21:06:05-07:00
List-Id: <comp.lang.ada>

"Randy Brukardt" <randy@rrsoftware.com> writes:
> "Keith Thompson" <kst-u@mib.org> wrote in message 
> news:lnh8785kge.fsf@kst-u.example.com...
>> Lucretia <laguest9000@googlemail.com> writes:
>>> On Thursday, 25 July 2019 08:26:29 UTC+1, Maciej Sobczak  wrote:
>>>> > The one concrete reason I've ever heard for using C or C++ instead
>>>> > of Modula-2 or Ada is that C/C++ allow you to perform pointer
>>>> > arithmetic
>>>>
>>>> Really? I would never consider that reason myself.
>>>
>>> Me neither, but then you can do pointer arithmetic in Ada, you just
>>> use normal numbers and convert to an address.
>>
>> I'm fairly sure there's no guarantee that the result of any such
>> conversion (which would have to use Unchecked_Conversion or something
>> equivalent, unless I've missed something) would be meaningful.
>
> And there is in C?? ;-)

No.  Did I imply that there is?

But C pointer arithmetic (without conversion to and from an integer
type) is well defined as long as you stay within a single (array)
object.  This isn't comp.lang.c, so I won't go into the details.

> Package System.Storage_Elements includes operations for directly doing 
> address arithmetic - you would have to do the multiplies on values of 
> Storage_Offset (which is an integer type) and then add/subtract those from 
> values of System.Address.

So it does.  The standard doesn't seem to say much about
what operations are well defined beyond suggesting that they
"should reflect the target environment semantics as closely as
is reasonable".

(C *needs* to go into a lot more detail about pointer arithmetic
because so much of the language depends on it.)

[snip]

To be clear, I'm not making any arguments for or against C or Ada.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */