Date: Sun, 21 Sep 1997 15:53:28 +1000 From: Bruce Evans <bde@zeta.org.au> To: mike@smith.net.au, perhaps@yes.no Cc: cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, cvs-gnu@FreeBSD.ORG, jonny@coppe.ufrj.br, phk@FreeBSD.ORG Subject: Re: cvs commit: src/gnu/usr.bin/as/config atof-ieee.c src/gnu/usr.bin/ld/rtld rtld.c src/gnu/usr.bin/man/man man.c Message-ID: <199709210553.PAA20728@godzilla.zeta.org.au>
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><C LAWYER>((void*)0) is a correct definition of NULL. The other
^^^^^another
>correct definition is 0.</C LAWYER>
Other correct definitions:
0L /* This has a different type than plain 0.
* It may be useful for hiding bugs on machines
* where sizeof(long) == sizeof(void *) &&
* sizeof(int) < sizeof(void *), and for finding
* bugs on machines where sizeof(long) >
* sizeof(void *).
*/
0UL /* A weirder type. This may be useful for
* finding misuses of NULL in integer context
*/
(2 + 2 != 4) /* A gratuitously complicated constant integral
* expression with value 0. This definition is
* not useful.
*/
(sizeof(char) - (int)1.1)
/* A gratuitously complicated not-obviously
* constant integral expression with value 0.
* This definition is not useful.
*/
Any of the above cast to `void *'.
/* Such definitions are just silly ways of writing
* ((void *)0), since they all have the same type
* and value.
*/
Other not-quite correct definitions:
0LL /* Will probably be correct in C9X, since C9X has
* long long (blech), and may already be correct
* in Gnu C. This may be useful for hiding bugs
* on machines where sizeof(long long) ==
* sizeof(void *) && sizeof(long) < sizeof(void *),
* and for finding bugs on machines where
* sizeof(long long) > * sizeof(void *).
*/
Bruce
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