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From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Uninitialized externals and statics.
Message-ID: <10810@smoke.BRL.MIL>
Date: 24 Aug 89 18:02:31 GMT
References: <2128@infmx.UUCP> <10764@smoke.BRL.MIL> <478.nlhp3@oracle.nl> <1989Aug19.053711.7462@twwells.com> <1786@crdgw1.crd.ge.com> <783@skye.ed.ac.uk> <7550@cg-atla.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 15

In article <7550@cg-atla.UUCP> fredex@cg-atla.UUCP (Fred Smith) writes:
-It is appropriate when testing a pointer against
-for being the null pointer to do a case, thusly:
-      if (foo == (char *)NULL)
-but then doing such a cast is ALWAYS appropriate, on any machine, since
-right after you leave the company somebody will get the bright idea
-of porting your code to some new whiz-bang-100 processor with weird
-architecture. This is also apprpriate on 8086-class machines, since
-the representation of a pointer, including the null pointer, will vary
-with memory model. (I hate segmented architectures.)

The cast would be necessary only if the implementor has screwed up the
definition of NULL.  #define NULL 0 would always be a correct implementation
definition for NULL, and the cast would never be necessary.  We explain this
in this newgroup every few months..