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From: dslg0849@uxa.cso.uiuc.edu (Daniel S. Lewart)
Newsgroups: comp.lang.pascal
Subject: Re: Help: How can I implement a record with variable width
Message-ID: <1991Jan7.004145.12324@ux1.cso.uiuc.edu>
Date: 7 Jan 91 00:41:45 GMT
References: <29636@shamash.cdc.com>
Sender: news@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at Urbana
Lines: 39

mpe@shamash.cdc.com (Mike Ebsen) writes:

> I would like to implement a variable record length record using Turbo
> pascal 5.5.
>
> type
>   element_type = record
>     number_of_items : word;
>     items : array [1..number_of_items] of real;
>   end;
>
> I've seen variant record structures before, but nothing which allows the
> size of an array to modulate as a function of a variable contained within
> the record.
-------------------------------------------------------------------------------
type
  TRealArray = array[1..10000] of Real;
  element_type = record
    number_of_items : word;
    ItemsPtr : ^TRealArray;
  end;

var
  Element: element_type;
Begin
  { ... Set Element.number_of_items ... }
  with Element do
    GetMem(  ItemsPtr, SizeOf(Real)*number_of_items );
  { ... }
  with Element do
    FreeMem( ItemsPtr, SizeOf(Real)*number_of_items );
  { ... }
End.
-------------------------------------------------------------------------------
Your problem calls for dynamic arrays, not variant records.  The above code
does what you want.

Daniel Lewart
d-lewart@uiuc.edu