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=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,c9d5fc258548b22a
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII
Path: 
 g2news2.google.com!postnews.google.com!i40g2000yqh.googlegroups.com!not-for-mail
From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: How do I write directly to a memory address?
Date: Tue, 8 Feb 2011 00:04:18 -0800 (PST)
Organization: http://groups.google.com
Message-ID: 
 <1f229967-d3cf-42b6-8087-c97ee08652f3@i40g2000yqh.googlegroups.com>
References: 
 <67063a5b-f588-45ea-bf22-ca4ba0196ee6@l11g2000yqb.googlegroups.com>
 <31c357bd-c8dc-4583-a454-86d9c579e5f4@m13g2000yqb.googlegroups.com>
 <05a3673e-fb97-449c-94ed-1139eb085c32@x1g2000yqb.googlegroups.com>
 <iimmvm$tsp$1@news.eternal-september.org> <8r86vgFc3uU1@mid.individual.net>
 <iimrem$udn$1@news.eternal-september.org>
 <19fh1chm74f9.11cws0j5bckze.dlg@40tude.net>
 <fa33fca1-c95b-4558-8a4c-7b3276366ffc@m13g2000yqb.googlegroups.com>
 <4d4ff70e$0$6886$9b4e6d93@newsspool2.arcor-online.net>
 <737a6396-72bd-4a1e-8895-7d50f287960e@d28g2000yqc.googlegroups.com>
 <4d5008a5$0$6879$9b4e6d93@newsspool2.arcor-online.net>
 <eda00084-fcc3-416c-bd3e-8b9e9c1a4b40@o13g2000yql.googlegroups.com>
 <4d5031fe$0$6765$9b4e6d93@newsspool3.arcor-online.net>
NNTP-Posting-Host: 153.98.68.197
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
X-Trace: posting.google.com 1297152261 19516 127.0.0.1 (8 Feb 2011 08:04:21
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Tue, 8 Feb 2011 08:04:21 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: i40g2000yqh.googlegroups.com; posting-host=153.98.68.197;
 posting-account=pcLQNgkAAAD9TrXkhkIgiY6-MDtJjIlC
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.6)
 Gecko/2009012111 Red Hat/3.0.6-1.el5 Firefox/3.0.6,gzip(gfe)
Xref: g2news2.google.com comp.lang.ada:17932
Date: 2011-02-08T00:04:18-08:00
List-Id: <comp.lang.ada>

Georg Bauhaus wrote:
>> Well, I came to wonder what intentions are conveyed by "void foo (int
>> arg)" and why modifying arg inside foo could be intentional. =A0Since I
>> came up with no convincing reason (the only reasons being variants of
>> premature optimization), I concluded that the possibility of "void foo
>> (int arg)" as opposed to "void foo (const int arg)" was a flaw in the
>> C language, that cost me a lot of effort.
>
> Ease of implementation when pushing parameters?
>
> void foo(int countdown)
> {
> =A0 while (--countdown) {
> =A0 =A0 fputc('.', stdout);
> =A0 }
> =A0 fputc('\n', stdout);
> }

That's what I meant by "variants of premature optimization".  If all
parameters were const, as in Ada, the programmer would simply declare
a local variable, like in Ada.  And the bug I was talking about would
become blatantly obvious.

BTW, like I said, *every* time I look at C code, I see a bug. In your
case, foo has undefined behavior if countdown is negative.

Also, note how the Ada version of this function does not use a
variable at all; it uses a for loop inside of which K is constant. And
it does not have your bug:

procedure Foo (Countdown : in Natural) is
begin
   for K in 1 .. Countdown loop
      Put ('.');
   end loop;
   Next_Line;
end Foo;

So, "ease of implementation" is not a good reason.  The thing you
implemented "easily" had a bug.

--
Ludovic Brenta.