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Path: utzoo!linus!philabs!cmcl2!seismo!harvard!bbnccv!keesan
From: keesan@bbnccv.UUCP (Morris M. Keesan)
Newsgroups: net.micro.68k,net.lang.c
Subject: Re: Question of Ignorance
Message-ID: <480@bbnccv.UUCP>
Date: Wed, 15-May-85 10:45:31 EDT
Article-I.D.: bbnccv.480
Posted: Wed May 15 10:45:31 1985
Date-Received: Thu, 16-May-85 21:44:54 EDT
References: <198@unccvax.UUCP>, <1427@bbncca.ARPA> <5590@utzoo.UUCP>
Organization: Bolt Beranek and Newman, Cambridge, MA
Lines: 20
Xref: linus net.micro.68k:706 net.lang.c:4717

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> > ... I recommend using one of the two constructs
> > 
> >     ( longptr == (long *)32 )
> > or  ( (int)longptr == 32 )
> > 
> > which are guaranteed to do what you want ...
> 
> Argh, WRONG!!  Turn that "(int)" into "(long)" and I might agree.  You
> have no guarantees that an int is long enough to hold a pointer.

Nor do you have any guarantees that a long is enough to hold a pointer.  I
was thinking that the (int) cast was sufficient because 32 is an int, but on
reflection I see that it might truncate longptr and give a result of TRUE if
the low-order int of longptr were 32.  I hereby retract my recommendation of
the second form, but stand by the first, which was my preference anyway.
---------------------------------
Morris M. Keesan
{decvax,ihnp4,etc.}!bbncca!keesan
keesan@bbn-unix.ARPA