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From: boogaard@ruunsa.fys.ruu.nl (Martin vdBoogaard)
Newsgroups: comp.lang.pascal
Subject: Re: Reuqest : Help with Enumeration Types
Keywords: enumeration type
Message-ID: <1827@ruunsa.fys.ruu.nl>
Date: 10 Dec 90 13:32:03 GMT
References: <3983@uniol.UUCP>
Organization: University of Utrecht, Dept. of Physics
Lines: 39

In <3983@uniol.UUCP> Arne.Gehlhaar@arbi.informatik.uni-oldenburg.de
(Arne Gehlhaar) writes:

% I have a problem with enumeration types.  I want to declare a type "measures"
% as a list of measurements: (g,kg,lb,oz, etc.) the actual type declaration is
% no problem, but I am not allowed to do input/output with them (says the
% Turbo Pascal 4.0 compiler)  So what is the use of those types.

They make your programs (more) readable. Supposing you're not able to use
enumerated types, you would have to use e.g. 0 for g, 1 for kg, 2 for lb
etc. What looks better:

  type  Measures  =  ( g, kg, lb, oz );      type  Measures  =  0..3;

  var   Weight_unit:  Measures;              var   Weight_unit:  Measures;

  case Weight_unit of                        case Weight_unit of
     g: <statement>;                           0: <statement>;
    kg: <statement>;             or:           1: <statement>;
    lb: <statement>;                           2: <statement>;
    oz: <statement>                            3: <statement>
  end;                                       end;

I'd prefer the first version.

I/O is a problem on most machines (and according to the ISO standard),
though. You'll have to read/write strings and convert them into a value,
valid for your enumerated type, using a case statement like the first
one in the above example.


Martin J. van den Boogaard         | Dept. of Atomic & Interface Physics
                                   | Debye Institute--Utrecht University
boogaard@fys.ruu.nl                | P.O. Box 80.000, NL-3508 TA Utrecht
boogaard@hutruu51.bitnet           | the Netherlands, +31 30 532904
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