Warp wrote:
>   OTOH, how many modern architectures have null pointers which are not
> all-zeros?

Now, me, being cynical, would say it's more "how many broken programs caused 
enough trouble that future architectures made sure that 0 is the bit pattern 
for null pointers?" :-)  I was using a AT&T 3B2 in the early 90's that had 
non-zero null pointers, but I think that's the only machine I ever used that 
supported C that didn't use 0.  Given they were insurance company computers, 
I wouldn't be surprised if they're still around. Legacy business systems 
have a way of living on for much longer than you'd think.

> you are just writing C for the PC, Mac and a few Unix computers out there,
> the rules can often be relaxed a bit.

Sure. It's language lawyering, not practical development. That's why I 
called it that. :-)

On the other hand, I wonder if segmented pointers (as in near and far 
pointers) used a segment of 0 to mean null for far pointers, or guaranteed 
that CS:0 and DS:0 (or whtever) would map to invalid pages. Hmmm...

-- 
   Darren New, San Diego CA, USA (PST)
   "We'd like you to back-port all the changes in 2.0
    back to version 1.0."
   "We've done that already. We call it 2.0."

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