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From: "Nick Roberts" <Nick.Roberts@dial.pipex.com>
Subject: Re: [Q] Returning Strings From A Function
Date: 1997/04/08
Message-ID: <01bc43b8$a4c441a0$09f682c1@xhv46.dial.pipex.com>#1/1
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References: <33454165.1658515@news.demon.co.uk>
 <33478738.2129057@news.demon.co.uk> <dewar.860338656@merv>
 <01bc42af$e32e3ea0$90f482c1@xhv46.dial.pipex.com> <E89sJq.62y@world.std.com>
Organization: UUNet PIPEX server (post doesn't reflect views of UUNet PIPEX)
Newsgroups: comp.lang.ada
Date: 1997-04-08T00:00:00+00:00
List-Id: <comp.lang.ada>



Robert A Duff <bobduff@world.std.com> wrote in article
<E89sJq.62y@world.std.com>...
> In article <01bc42af$e32e3ea0$90f482c1@xhv46.dial.pipex.com>,
> Nick Roberts <Nick.Roberts@dial.pipex.com> wrote:
> >   FS: Filename_String := ""; -- unconstrained type, so must be
initialised
> 
> FS is forever constrained to length zero.
> 
> >   FS := Text_IO.Name(F); -- constraint error raised if longer than 12
> 
> No, this will raise C_E, unless the name is of length zero.
> 
> Ada's built-in arrays cannot change size.


Argh! The embarrassment! Sudden brainstorm, Bob (my excuse being that I am
using a lot of different languages at the moment (pretty feeble, eh?)).
Anyway, what I _should_ have written was this...


declare
   F: Text_IO.File_Type;
   ...
   type Filename_String is array (1..12 range <>) of Character;
   type Filename_Ref is access Filename_String;
   ...
   S: Filename_Ref;
   ...
begin
   ...
   S := new Filename_String'(Text_IO.Name(F)); -- constraint error raised
if name longer than 12 chars
   ...
   Text_IO.Put("Name of file is: "+String(S.all)); -- note the need to
dereference and convert
   ...
end;


John: I hope I did not end up confusing you. Many apologies. The above will
actually work, and will hopefully be a relatively simple solution to your
problem.

Nick.