Path: utzoo!attcan!uunet!husc6!think!ames!pasteur!ucbvax!hplabs!sdcrdcf!csun!polyslo!dorourke
From: dorourke@polyslo.UUCP (David O'Rourke)
Newsgroups: comp.sys.mac.programmer
Subject: MPW Pascal Bug? Or am I wrong.
Message-ID: <3203@polyslo.UUCP>
Date: 18 Jun 88 04:33:51 GMT
Reply-To: dorourke@polyslo.UUCP (David O'Rourke)
Organization: Cal Poly State University -- San Luis Obispo
Lines: 35

This isn't a serious problem, but I thought I'd share it with netland anyways.
Given the following peice of code:

procedure doSomething;
  var
    X, Y : INTEGER;
    Z    : LONGINT;
  begin
    Z := X * Y;
  end;  {doSomething}

If X*Y causes an overflow and I have overflow checking turned off it stores
the wrong result, usually negative, in Z even though Z is a LONGINT.  Now is
this what the compiler is suppose to do, or is it suppose to convert to the
LONGINT.

My problem is that the multiply seems to be taking place in 16-bit precision
even thought there is a LONGINT that it's being assigned too.

I know the solution, {read work-around}, to this problem.  But I was under
the impression that the compiler would allow this sort of math and that I
wouldn't get the overflow stored in the LONGINT, but I would get the actual
value of the multiply, anyone care to comment on this.  I'd appreciate any
help in understanding why the compiler can't deal with the code as is and
yeild the correct result.

I'm running the latest version of MPW 2.0 and the lastest version of MPW
pascal 2.0.

Thanks for any help.

-- 
David M. O'Rourke

Disclaimer: I don't represent the school.  All opinions are mine!