22 Sep
2020
22 Sep
'20
2:46 a.m.
Steve Nickolas wrote in
<alpine.DEB.2.21.2009201654300.10605(a)sd-119843.dedibox.fr>:
|On Sun, 20 Sep 2020, Doug McIlroy wrote:
|
|>> (Of course, that assumes NULL is 0, but I don't think I've run into
any
|>> architecture so braindead as to not have NULL=0.)
|>
|> It has nothing to do with machine architecture. The C standard
|> says 0 coerces to the null pointer. NULL, defined in <stddef.h>,
|> is part of the library, not the language. I always use 0,
|> because NULL is a frill.
|>
|> Doug
|
|I was under the impression that there was explicitly no requirement that a
|null pointer be 0, and that there was at least one weird system where that
|wasn't true - that it just so happened that null points to 0 on certain
|CPUs and that 0=NULL *happens* to work on most CPUs but wasn't guaranteed.
|(In fact, I read that my habit of using 0 for NULL relied on a faulty
|assumption!)
|
|I mean, I've never actually used a CPU/OS/compiler where it wasn't true,
|but...
I remember having to use __null for __GNUC__>=3 because 0x0 (what
is used for my NIL macro before, this was C++) did not work out
well. (Could have been compiler bug, of course .. but i just
remembered it when reading your post.)
--steffen
|
|Der Kragenbaer, The moon bear,
|der holt sich munter he cheerfully and one by one
|einen nach dem anderen runter wa.ks himself off
|(By Robert Gernhardt)