[TUHS] reviving a bit of WWB

Greg A. Woods woods at robohack.ca
Wed Feb 3 09:08:42 AEST 2021


At Sun, 20 Sep 2020 17:35:52 -0400, John Cowan <cowan at ccil.org> wrote:
Subject: Re: [TUHS] reviving a bit of WWB
>
> When 0 is coerced implicitly or explicitly to a pointer type, it becomes a
> null pointer.  That's true even on architectures where all-bits-zero is
> *not* a null pointer.  However, in contexts where there is no expected
> type, as in a call to execl(), the null at the end of the args list has to
> be explicitly cast to (char *)0 or some other null pointer.

Yeah, that's more to do with the good/bad choice in C to do or not do
integer promotion in various situations, and to default parameter types
to 'int' unless they are, or are cast to, a wider type (and of course
with the rather tricky and almost non-portable way C allows variable
length argument lists, along with the somewhat poor way C was cajoled
into offering function prototypes to support separate compilation of
code units and the exceedingly poor way prototypes deal with variable
length argument lists).

--
					Greg A. Woods <gwoods at acm.org>

Kelowna, BC     +1 250 762-7675           RoboHack <woods at robohack.ca>
Planix, Inc. <woods at planix.com>     Avoncote Farms <woods at avoncote.ca>
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