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From: stanley@phoenix.com (John Stanley)
Newsgroups: comp.lang.c
Subject: Re: the nil pointer is not zero (was TC 2.0 oddity - me or ?)
Message-ID: <4kqLs10w163w@phoenix.com>
Date: 14 Nov 90 01:13:26 GMT
References: <27636@mimsy.umd.edu>
Organization: One Man Brand
Lines: 27


chris@mimsy.umd.edu (Chris Torek) writes:

> In article <s64421.658489804@zeus> s64421@zeus.usq.EDU.AU (house ron) writes:
> >Zero is actually a perfectly legitimate address, but it got snaffued
> >by C to stand for a NULL pointer.
> 
> This is true in many *implementations*, but it is not part of C itself.
> 
> On computers on which address location zero has `interesting' contents
> (e.g., a boot reset vector, or simply regular memory), implementations
> are faced with two choices:  either the nil pointer pointer to some

   And some operating systems will not map address 0 into the process
space, which makes 0 the NULL pointer, and dereferencing it immediately
painful. I remember reading that those systems which do not map 0
addresses are a direct result of protecting against the most common
invalid pointer reference.





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><
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