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From: Jerry <lanceboyle@qwest.net>
Newsgroups: comp.lang.ada
Subject: How to exit a loop with keyboard input
Date: Sun, 11 Apr 2010 21:12:38 -0700 (PDT)
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Date: 2010-04-11T21:12:38-07:00
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[Sorry for the cross-post.]

I have a loop which is doing a repetitive calculation. Sometimes the
loop runs a long time and I want to manually cause the loop to be
exited but have the program continue running, for example to save some
results to a file or do other calculations. Preferably I would just
hit a key or key combination.

I thought Get_Immediate would work (reading Cohen's book) but it does
not do what I want. For example, the following program stops looping
and requires me to hit RETURN even if I hit another key first. It
continues looping (very slowly) if I hold down the RETURN key.

I don't mind using GNAT-specific stuff as long as it gets the job
done.

Thanks.

Jerry


with Ada.Text_IO;
use  Ada.Text_IO;
procedure key is
    i         : Integer;
    Keystroke : Character;
    Available : Boolean;
begin
    i := 0;
    loop
        Put(Integer'Image(i));
        Get_Immediate(Keystroke, Available);
            if Available then
                if Keystroke = 'q' then
                    exit;
                end if;
            end if;
        i := i + 1;
    end loop;
    Put_Line("Finished");
end key;