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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Subject: Re: Beginer problem: variable array size
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Date: Thu, 19 Sep 2002 00:43:11 GMT
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Date: 2002-09-19T00:43:11+00:00
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"Nacho" <NACHANGA@terra.es> writes:

> That does not resolve the problem. I need to change the size of the array
> after it has been created. With your solution once array_called_p has been
> created it will never change its size.

Right.  You've been admonished about considering the "proper Ada" way of
allocating arrays local to a scope.  You should consider those, but
those require that the array size be known at the point of creation.
There are many cases where you really need to change the size of an
existing array (despite the admonishments that this is rare -- I think
it's common).

> The solution in c++ is easy as I posted before. Simply free the memory and
> reserve new memory to hold the new size of the array.

The solution is what Ludovic Brenta said: you do essentially the
same as in C++ -- you deallocate and reallocate the array.

And Pascal Obry gave good advice to encapsulate this in an abstraction.
Look at the implementation of Ada.Strings.Unbounded, which is a
size-changing array of characters.

It's usually better to allocate exponentially-more space each time a
reallocate-and-copy is needed.

- Bob