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Posting-Version: version B 2.10.2 9/18/84; site watmath.UUCP
Path: utzoo!watmath!kpmartin
From: kpmartin@watmath.UUCP (Kevin Martin)
Newsgroups: net.lang.c
Subject: Re: sizeof, ptrs, lint, portability
Message-ID: <11406@watmath.UUCP>
Date: Sat, 9-Feb-85 16:47:46 EST
Article-I.D.: watmath.11406
Posted: Sat Feb  9 16:47:46 1985
Date-Received: Sun, 10-Feb-85 06:38:31 EST
References: <8121@brl-tgr.ARPA>
Reply-To: kpmartin@watmath.UUCP (Kevin Martin)
Organization: U of Waterloo, Ontario
Lines: 28
Summary: 

In article <8121@brl-tgr.ARPA> cottrell@nbs-vms.ARPA writes:
>-) I apologize for calling (presumably someone's favorite) machines `weird'
>   or `braindamaged'. Let's say `less capable'.
Let's say 'capable of doing things other than you want done'.
I doubt that a pianist would like being called 'weird', 'braindamaged',
or even 'less capable' just because you happen to want to hear her play a
trombone.

>   Allowing any other value to actually be stored breaks this. Besides,
>   SHOW ME A C THAT USES ANYTHING OTHER THAN ZERO ON ANY MACHINE!!!
>   K&R says of pointer to integer conversions: "The mapping funxion is
>   also machine dependent, but is intended to be unsurprising to those
>   who know the machine." I would be surprised at nonzero null ptrs.
Then you obviously don't know the machine.
A Honeywell DPS8, running CP-6, uses the bit pattern 06014 (36 bits)
as the null pointer (byte offset zero in segment number 014).
The pointer to int casts (and back) are accomplished by ex-oring
with this value.
The value 0 CAN'T be used, since this is a valid pointer.

>-) How many of you port what percentage of programs? I thought the
>   intent of the standard was to not break existing programs.
I don't think it does break programs (except those which use =
and initializers without the '='). Your programs will continue
to run on systems on which they previously ran. You may get
more warnings when you compile them, though.

                     Kevin Martin, UofW Software Development Group