[TUHS] reviving a bit of WWB

Steve Nickolas usotsuki at buric.co
Mon Sep 21 06:58:51 AEST 2020


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...

-uso.


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