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From: jfr@locus.com (Jon Rosen)
Newsgroups: comp.lang.pascal
Subject: Re: User defined ordinal types
Message-ID: <19956@oolong.la.locus.com>
Date: 27 Nov 90 22:14:46 GMT
References: <527@shum.UUCP>
Organization: Locus Computing Corp, Los Angeles
Lines: 41

In article <527@shum.UUCP> seran@vms.huji.ac.il writes:
>
> I am programming a pascal program using the vm compiler pascal. I am defining
> a user defined type to be:
> day_type= (sun,mon,tue,wed,thu,fri,sat);
> I want to cycle through the days of the week but return to sun after sat.
> I'd like to do this using a succ(day) which is in a loop counting the
> days of the month. Also I would like to set the loop to start at Monday.
> Is there any way of assigning the position to a user def. type?
> And doing what I want to do? Thank you in advance, Eran...

You are going to have to write your own function in Pascal that gets the
next day for you...
 
Function NextDay(ThisDay:day_type):day_type;
Begin
  If ThisDay = Sat
  Then NextDay := Sun
  Else NextDay := Succ(ThisDay);
End;
 
This function will hide the details of cycling through the
enumerated datatype.  

You can use this in an endless type of loop such as:
 
CurrDay := Mon;
While True Do Begin
  <loop body>
  CurrDay := NextDay(CurrDay);
End;
 
Since the predefined identifier True is always true, the
loop will continue endlessly cycling thru the days of the
week.  You will need some kind of a Break, Leave
Exit or Goto to get out of the loop.  I believe the
VM Pascal compiler has a Leave statement.
 
Good luck.

Jon Rosen