Re: Variable-length arrays (from a C programmer)

[matthew_heaney@acm.org (Matthew Heaney)]

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);

...