Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!cs.utexas.edu!uunet!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.lang.c
Subject: Re: Uninitialized externals and statics
Message-ID: <162@crdos1.crd.ge.COM>
Date: 25 Aug 89 14:36:37 GMT
References: <2128@infmx.UUCP> <4700042@m.cs.uiuc.edu>
Organization: GE Corp R&D Center
Lines: 25

In article <4700042@m.cs.uiuc.edu>, kenny@m.cs.uiuc.edu writes:
> This is BROKEN.  How many times do those of us that understand this
> have to shout it?  When a pointer is compared with an integer, it is
> implicitly promoted to an integer.  Saying
	[ many things ]

  I think you may have missed the original posters point (he didn't shout
it). He was saying that on his machine a NULL pointer is not all bits zero.
Therefore if a C implementation set the pointer to "all bits zero" the
result would not be a NULL pointer, and would not compare equal to NULL.

  The ANSI standard calls for initialization to zero *cast to the
appropriate type* here, which would be another value. His compiler may be
non-conforming, but the point he was making has nothing to do with
promoting pointers to int (actually I think it's the other way round, since
an int may not be able to hold a pointer).

  The standard also allows NULL to be a pointer type ((void *) 0) which
would make it somewhat arcane to convert two pointer to integers to compare
them. 
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
"The world is filled with fools. They blindly follow their so-called
'reason' in the face of the church and common sense. Any fool can see
that the world is flat!" - anon