Hi Jakub, On 7/25/22 20:57, Jakub Wilk wrote:
* Alejandro Colomar <alx.manpages@xxxxxxxxx>, 2022-07-24, 21:19:+.B "#define NULL ((void *) 0)" +.fi +.SH DESCRIPTION +.B NULL +represents a null pointer constant. +.PP +According to POSIX, +it shall expand to an integer constant expression with the value +.B 0 +cast to type +.IR "void *" .Might be worth noting that the cast requirement was added only in POSIX.1-2008 aka SUSv4.+.SH CONFORMING TO +C99 and later;It's in C89 too.
Michael and I agreed that for new pages, we're going to ignore the C89 standard, as almost all current code assumes C99 is available, at least to a certain degree of support.
The same as POSIX.1-1990 is also ignored for simplicity, and we start counting from POSIX.1-2001.
I'm not sure if documenting C89 provides any value (apart from historical curiosity, that is).
+.I NULL \- NULL +is, surprisingly, undefined behavior, according to ISO C.FWIW, I don't find it surprising at all.
Then you might perhaps find it surprising that in C++ it's defined to be 0. Cheers, Alex -- Alejandro Colomar <http://www.alejandro-colomar.es/>
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