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From: KVC@ENGVAX.SCG.HAC.COM (Kevin Carosso)
Newsgroups: comp.os.vms
Subject: Re: Language question
Message-ID: <8705230653.AA06889@ucbvax.Berkeley.EDU>
Date: Fri, 22-May-87 15:21:00 EDT
Article-I.D.: ucbvax.8705230653.AA06889
Posted: Fri May 22 15:21:00 1987
Date-Received: Sat, 23-May-87 19:02:02 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 35

> I'm a bit rusty in C and Pascal.  Can anyone tell me if either of these
> (or another HLL) allows the user to cast an array into an arbitrary type
> at runtime and then read/write or otherwise manipulate it as such?  Do I
> have to use MACRO to do what I want?  Thanks to all who reply.
> -Ric Steinberger

Through a non-standard extension, VAX Pascal allows type-casting.  You could
create a VAX Pascal routine that accepts the array and some indicator of the
type and then operate on the elements of the array while casting them.

For example, here's a simple Pascal program that treats an array as longwords
or bytes...

--------------------------------------------------------------
program z (input, output);

type
  byte_array = array [0..7] of [byte] 0..255;
  long_array = array [0..1] of unsigned;

var
  x : long_array := (1,2);
  i : integer;

begin
  for i := 0 to 1 do
    writeln (x::long_array[i]);   (* don't need the cast operator "::" here *)
  writeln;
  for i := 0 to 7 do
    writeln (x::byte_array[i]);
end.
--------------------------------------------------------------

        /Kevin Carosso                           kvc%engvax@oberon.usc.edu
         Hughes Aicraft Co.                      kvc@engvax.scg.hac.com