Date: Sun, 23 Sep 2001 10:49:28 -0700 From: Bakul Shah <bakul@bitblocks.com> To: Bruce Evans <bde@zeta.org.au> Cc: Murray Stokely <murray@FreeBSD.org>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/usr.sbin/sysinstall command.c config.c Message-ID: <200109231749.NAA01962@glatton.cnchost.com> In-Reply-To: Your message of "Sun, 23 Sep 2001 18:06:02 %2B1000." <20010923180124.I13390-100000@delplex.bde.org>
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> > Use '%p' when printing out the address of a function.
> > sizeof(int) != sizeof(long)
>
> %p is for printing pointers of type "void *". It is unsuitable for
> printing arbitrary pointers to objects. It is especially unsuitable
> for printing pointers to functions.
I have an old (1997) working draft of C9X which says
6.2.2.3 Pointers
[#1] A pointer to void may be converted to or from a pointer
to any incomplete or object type. A pointer to any
incomplete or object type may be converted to a pointer to
void and back again; the result shall compare equal to the
original pointer.
Since any object ptr may be converted to %p, you can do, e.g.
printf("...%p...", ..., (void*)&some_function, ...);
But you seem to be saying this is not be a valid conversion.
Have things changed since then or is a function not
considered an "object"? I would appreciate a C standard
reference ( i.e. chapter and verse!) that shows this is
invalid.
At any rate %p is preferable to %x or %lx even if not
properly pedantic. I have used machines with segmented
address space (an NEC unix machine in mid80s though I forget
the model number) where %p would give you <seg>:<addr> but %x
or %lx would be wrong.
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