Path: utzoo!attcan!uunet!tektronix!reed!barry
From: barry@reed.UUCP (Barry Smith)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Overflow Checking from within Pasca
Keywords: Pascal Standard
Message-ID: <10530@reed.UUCP>
Date: 5 Oct 88 22:24:01 GMT
References: <4276@polyslo.CalPoly.EDU> <900006@zaphod> <429@husc6.harvard.edu>
Reply-To: barry@reed.UUCP (Barry Smith)
Organization: Blue Sky Research, Portland OR
Lines: 19

In article <429@husc6.harvard.edu> singer@endor.UUCP (Rich Siegel) writes:
>... Pascal simply has no provisions for supporting
>unsigned arithmetic, as C does. In any pascal, the only way to work
>with unsigned values is to disable overflow and range checking.
>
>		--Rich

Pascal allows specification of "unsigned integers", although there is no
specification of the mapping to the underlying hardware, of course. The
declaration "var I: 0..65535" will declare an unsigned range of integers,
ahd the declaration "type unsigned = 0..65535" specifies a new type that
should, in a conforming implementation, range-check properly.

There are several Pascal compilers that will perform the obvious mapping
to the underlying hardware, although Lightspeed Pascal is apparently not
one of these.  (Nor is MPW Pascal, alas.)

Barry Smith
Blue Sky Research