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=-0.9 required=5.0 tests=BAYES_00,FORGED_GMAIL_RCVD,
	FREEMAIL_FROM autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: a07f3367d7,fb17569fccf2604b
X-Google-Attributes: gida07f3367d7,public,usenet
X-Google-NewGroupId: yes
X-Google-Language: ENGLISH,ASCII
Path: 
 g2news2.google.com!postnews.google.com!j19g2000yqk.googlegroups.com!not-for-mail
From: Vadim Godunko <vgodunko@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Trouble writing Ada callback from C
Date: Sat, 12 Sep 2009 11:40:27 -0700 (PDT)
Organization: http://groups.google.com
Message-ID: 
 <241a6745-0848-4bd0-bb1b-1e826e084911@j19g2000yqk.googlegroups.com>
References: <e54f9d08-3083-4c98-974f-9695005679b3@x6g2000prc.googlegroups.com>
NNTP-Posting-Host: 93.178.77.161
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
X-Trace: posting.google.com 1252780827 9850 127.0.0.1 (12 Sep 2009 18:40:27
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Sat, 12 Sep 2009 18:40:27 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: j19g2000yqk.googlegroups.com; posting-host=93.178.77.161;
	posting-account=niG3UgoAAAD7iQ3takWjEn_gw6D9X3ww
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.13)
	Gecko/2009080200 SUSE/3.0.13-0.1.2 Firefox/3.0.13,gzip(gfe),gzip(gfe)
Xref: g2news2.google.com comp.lang.ada:8307
Date: 2009-09-12T11:40:27-07:00
List-Id: <comp.lang.ada>

On Sep 11, 11:57=A0am, Jerry <lancebo...@qwest.net> wrote:
> I have a problem with writing an Ada procedure, used as a callback
> from C, in which one of the arguments is an output char * (in the C
> version). The actual length of the returned "string" isn't known at
> calling time, even though the caller apparently allocates 40
> characters (see below). However, the actual number of characters
> returned by the C version is less than 40.
>
> My problem is how to pass probably a char_array back out which is the
> correct length, but which length is not known at the time the Ada
> callback is called from C.
>

subtype constrained_char_array is Interfaces.C.char_array (1 .. 40);

procedure Y (X : out constrained_char_array);
pragma Convention (C, Y);