Date: Wed, 8 Mar 2000 15:22:15 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender: eliz AT is
To: Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
cc: djgpp-workers AT delorie DOT com
Subject: Re: iso646.h and some questions
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On Wed, 8 Mar 2000, Hans-Bernhard Broeker wrote:

> On Wed, 8 Mar 2000, Eli Zaretskii wrote:
> 
> > On Wed, 8 Mar 2000, Hans-Bernhard Broeker wrote:
> > 
> > > > > 	#undef NULL
> > > > > 	#define NULL 0
> > > > 
> > > > Won't this make trouble in C++ programs?
> > > 
> > > Why should it? This is the exact definition found in current DJGPP
> > > headers, already.
> > 
> > See stdlib.h.  Recent versions of libstdc++ define NULL to something like 
> > __null.  There was a thread about this on djgpp-workers several months 
> > ago, and I think on c.o.m.d. as well; you might read it for details.
> > 
> > I guess we fixed stdlib, but not stddef...
> 
> When would that have been done? I just downloaded a spare copy of
> djdev203.zip, dated Jan 07, 2000, to this Linux box, and this is what I
> got:
> 
> ~/Ltmp/djgpp> find include -type f | xargs grep 'define.*NULL'

Wrong command.  It misses these two lines from stdlib.h:

  /* Some programs think they know better... */
  #undef NULL

This is in stdlib.h because the original version caused compiler 
warning/errors (I forget which) when compiling C++ programs.  The
reason turned to be that the C++ compiler has its own definition
of NULL, pulled from some C++ header.

> As you can see, it's '0', everywhere in the C headers.

Yes, because it's good enough for C.  But I was talking about including 
these headers in C++ programs.