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From: rns@se-sd.SanDiego.NCR.COM (Rick Schubert)
Newsgroups: comp.lang.c
Subject: Re: Seven Original Sins of K&R (Long)
Message-ID: <3945@se-sd.SanDiego.NCR.COM>
Date: 2 Oct 90 14:26:28 GMT
References: <12780@sdcc6.ucsd.edu> <1990Sep26.163927.26084@dg-rtp.dg.com> <1990Sep26.193626.721@phri.nyu.edu> <1990Sep27.073730.26575@warwick.ac.uk> <1990Sep27.131329.26616@phri.nyu.edu> <1990Sep28.144753.23727@zoo.toronto.edu>
Organization: NCR Corporation, Systems Engineering - San Diego
Lines: 23

[I know I should probably let this go since this is a dead issue, but I
 couldn't resist improving on Henry's answer.  I hope I'm not missing
 something, since I'm surprised he didn't also say what I'm going to.]

In <1990Sep28.144753.23727@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:

>In article <1990Sep27.131329.26616@phri.nyu.edu> roy@phri.nyu.edu (Roy Smith) writes:
>>... I meant to
>>write:
>>
>>#define NULL (""[0])

>Roy, apart from not being a compile-time value, which limits its use,
>this is exactly and precisely equivalent to

>#define	NULL	0

Since (""[0]) is not a compile-time value (I assume that's the same thing
as a constant expression), it is also not a null-pointer constant.
It DOES have the value 0, but the only arithmetic expressions that 
are null pointers are those that are constant expressions evaluating to 0.

-- Rick Schubert (rns@se-sd.sandiego.NCR.COM)