Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!mcvax!hp4nl!maestro!fransvo
From: fransvo@maestro.htsa.aha.nl (Frans van Otten)
Newsgroups: comp.lang.modula2
Subject: Re: type conversion question
Message-ID: <951@maestro.htsa.aha.nl>
Date: 1 Jun 89 14:39:43 GMT
References: <2027@csuna.csun.edu>
Reply-To: fransvo@htsa.UUCP (Frans van Otten)
Organization: AHA-TMF (Technical Institute), Amsterdam The Netherlands
Lines: 25

Jeff Boeing writes:

>I couldn't find this anywhere in Wirth's book (4th edition), so here goes:
>
>How do you convert from a cardinal or integer type to an enumerated type?
>I would like very much to keep a particular enumerated type in a program I'm
>writing, but this program requires that some data of that type be written to
>and read from a file.  If x is of my enumerated type, it's easy enough to save
>it to a file by saying "WriteInt (ORD(x))" (after redirecting output, of
>course), but how do I read that value back in?

I don't know about the 4th edition, but in the 3rd edition such a procedure
is described.  In paragraph 10.2, "Standard procedures", on page 162:

  VAL(T, x)  The value with ordinal number x and with type T.  T is any
	     enumeration type, or CHAR, INTEGER, or CARDINAL.
	     VAL(T, ORD(x)) = x, if x is of type T.

( Does anybody know why I never see anything about LONGINT
  or LONGREAL, except in the paragraph about basic types ? )

-- 
Frans van Otten                     |   fransvo@maestro.htsa.aha.nl    or
Algemene Hogeschool Amsterdam       |   fransvo@htsa.uucp              or
Technische en Maritieme Faculteit   |   [[...!]backbone!]htsa!fransvo