Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mcnc!uvaarpa!vger.nsu.edu!g_harrison
From: g_harrison@vger.nsu.edu
Newsgroups: comp.lang.pascal
Subject: Enumeration Inverse- was Request : Help with E Types
Message-ID: <357.27648291@vger.nsu.edu>
Date: 11 Dec 90 10:54:09 GMT
References: <3983@uniol.UUCP> <1990Dec10.180345.31492@wpi.WPI.EDU>
Lines: 35

In article <1990Dec10.180345.31492@wpi.WPI.EDU>, kamal@wpi.WPI.EDU (Kamal Z Zamli) writes:
> In article <3983@uniol.UUCP> Arne.Gehlhaar@arbi.informatik.uni-oldenburg.de (Arne Gehlhaar) writes:

I am familiar with several versions of Pascal extensions and believe that those
with enumeration IO facilities are providing important functionality.  I have a
different "complaint."  

When working with CHAR type we have CHR as the inverse of ORD.  With general
enumerated types we don't.  

For example in Ada there is

type FUZZY = (YES, NO, MAYBE);

F : FUZZY := NO;

FUZZY'POS(F) is 1
FUZZY'VAL(1) is NO

FUZZY'POS(FUZZY'VAL(2)) is 2
FUZZY'VAL(FUZZY'POS(MAYBE)) is MAYBE

We can certainly find the Nth (N = 0...) element in an enumerated type in
Pascal by searching for it, but are there some tricks (Machine-Dependent or
otherwise) to provide an inverse to ORD that do not involve searching?

George....

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