Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: Re: machine specific languages (was: Re: C machine)
Message-ID: <7167@brl-smoke.ARPA>
Date: 22 Jan 88 21:12:45 GMT
References: <9907@mimsy.UUCP> <5360001@hpisla.HP.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 13

In article <5360001@hpisla.HP.COM> wolpert@hpisla.HP.COM (David Wolpert) writes:
>... but the 32-bit case is the same: the difference between two unsigned
>32-bit pointers can exceed the range of a 32-bit 2's complement number.
>Maybe ptrdiff_t wasn't intended to handle the case of more than half of
>the machine's address space allocated to one object?

Yes, on a 32-bit "long" machine, ptrdiff_t cannot represent the difference
of pointers TO CHARS in an array having more than 2^31 chars.  Pointers
to things larger than chars have no such problem.

We couldn't think of any clean way to fix this part of the pointer-diff
problem, and decided it wasn't very important in practice.  Who would
actually have an application that needs to do this?