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Newsgroups: comp.lang.ada
Path: sparky!uunet!math.fu-berlin.de!dww
From: dww@math.fu-berlin.de (Debora Weber-Wulff)
Subject: Membership in "set" of characters
Message-ID: <J6QBBP3L@math.fu-berlin.de>
Sender: news@math.fu-berlin.de (Math Department)
Organization: Free University of Berlin, Germany
Date: Fri, 19 Mar 1993 17:06:19 GMT
Date: 1993-03-19T17:06:19+00:00
List-Id: <comp.lang.ada>

This is another one of those "why won't this work?" for the experts.
I'm stumped. As far as I can decode the LRM and
see from 2 textbooks I consulted, this ought to work.

-- muell3.ada
--
-- Why won't membership work here?
--
with text_io; use text_io;

procedure muell3 is
type affirmatives is ('y', 'Y', 'j', 'J', 'o', 'O');
  ch : CHARACTER;
  okay : Boolean;

begin
  get (ch);
  -- The next statement gets flagged with
  -- type clash in membership test [LRM 4.5.2/10]
  okay := ch IN affirmatives;

  -- Is this because there's the clause
  -- for CHARACTER use (1, 2, ... 128) in the standard?

end muell3;

This one was one of my favorites in Pascal! I'm currently 
quite frustrated with the type system after writing a little program
to calculate the return on investment. I had declared
one type for the interest and one for the DM amount, one was a float and
one was a fixed value. After hours of agony to get the conversion right
as the silly FIXEDs needed an explicit conversion after each * and /
I found that 1000 DM (FIXED) * 0.03 (FLOAT) was equal to 31.98 !!!. 
I'd love for the bank to calculate my interest that way! It finally
worked when both were FLOAT values. Now all I wanted to add was a loop
to calculate the values again, and I get blown out of the water by 
Meridian's 4.1 type checker again. 
Is it me? Is it Meridian? Or is this the agony of using Ada?
8
-- 
Debora Weber-Wulff, Professorin fuer Softwaretechnik
snail: Technische Fachhochschule, FB Informatik, 
       Luxemburgerstr. 10, 1000 Berlin 65
email: dww@informatik.tfh-berlin.dbp.de