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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,6edeb2a39724bbc0
X-Google-Attributes: gid103376,public
From: matthew_heaney@acm.org (Matthew Heaney)
Subject: Re: Variable-length arrays (from a C programmer)
Date: 1998/04/28
Message-ID: <matthew_heaney-ya023680002804982248550001@news.ni.net>#1/1
X-Deja-AN: 348649670
Content-Transfer-Encoding: 8bit
References: <353F9B75.3019A7A4@AlliedSignal.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Organization: Network Intensive
Newsgroups: comp.lang.ada
Date: 1998-04-28T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <353F9B75.3019A7A4@AlliedSignal.com>, "Paul T. McAlister"
<Paul.McAlister@AlliedSignal.com> wrote:

(start of quote)
In "C" (see example), I can define an array of messages for each page,
then define an array of pages for the whole thing.
I don't have to worry about string length or number of items defined in
the arrays, the compiler handles all of that for me.

I have not been able to figure out how to do the equivalent thing in
Ada.
I don't know how to define strings without setting the length to the
maximum length string I will have, which wastes a lot of space.
I think I know how to define the variable length arrays for the messages
for each screen, but I don't know how to define an array type of these
arrays of string for each page (since they are different types because
they are different lengths).
I am using Ada83.
(end of quote)

You stated clearly that you are using Ada 83.  However, I wanted to let you
know that in Ada 95 there's a predefined string type that does exactly what
you want.  It's called Ada.Strings.Unbounded.Unbounded_String.

In Ada 83, you'll have to roll your own dynamic string abstraction,
something like

package Unbounded_Strings is

   type Unbounded_String is limited private;

   procedure Append (S : String; To : in out Unbounded_String);

   procedure Clear (Source : Unbounded_String);

...