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From: Ken Garlington <garlingtonke@lmtas.lmco.com>
Subject: Zoo question
Date: 1996/08/12
Message-ID: <320F16B6.6944@lmtas.lmco.com>#1/1
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organization: Lockheed Martin Tactical Aircraft Systems
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newsgroups: comp.lang.ada
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Date: 1996-08-12T00:00:00+00:00
List-Id: <comp.lang.ada>


Here's a little brain teaser we received recently. Assuming no typos or 
other obvious syntax errors, will the Fill procedure work in Ada 83?

package Zoo is

  type Animal_ID is range 1 .. 5; -- yes, an enumeration type might be
 	                                -- better, but it spoils the example!

  subtype Cage_ID is Positive range 1 .. 12;

  type Cage_Row is array (Cage_ID) of Animal_ID;

  -- Fill fills a row of cages with various animals, in sequential order
  -- with alternating animals
  procedure Fill ( Cages : in out Cage_Row );

end Zoo;

package body Zoo is

  procedure Fill ( Cages : in out Cage_Row ) is
    Next_Animal : Animal_ID := Animal_ID'First;
  begin -- Fill
    for Cage in Cages'Range loop

      Cages(Cage) := Next_Animal;

      Get_Next_Animal: begin -- look carefully at this code!
        Next_Animal := Animal_ID'Succ(Next_Animal);
      exception
        when others => Next_Animal := Animal_ID'First;
      end Get_Next_Animal;

    end loop;
  end Fill;

end Zoo;