From owner-cvs-all  Sat Jun 16 21:58:26 2001
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Date: Sun, 17 Jun 2001 14:56:00 +1000 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
Cc: Jonathan Lemon <jlemon@flugsvamp.com>,
	Jonathan Lemon <jlemon@FreeBSD.org>, cvs-committers@FreeBSD.org,
	cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/usr.sbin/rarpd rarpd.c
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On Sat, 16 Jun 2001, Garrett Wollman wrote:

> <<On Sat, 16 Jun 2001 11:09:40 -0500, Jonathan Lemon <jlemon@flugsvamp.com> said:
> 
> > Yes - sizeof() appears to be a 'long int' on the alpha, but an 'int'
> > on the i386.
> 
> The correct way to print the result of the `sizeof' operator using
> `printf()' in C89 is with the `%lu' format (and the argument cast to
> `unsigned long'), and in C99 is with the `%ju' format (and the
> argument cast to `uintmax_t').  This is true always, on every
> architecture, and has been true since C89 introduced size_t to begin
> with.

These are not incorrect ways.  They may be gratuitously inefficient.
E.g., the value returned by sizeof() may be known to be smaller than
INT_MAX, and then you can print it using %d after casting it to int.
Of course, efficiency of printf is usually unimportant.

Someone mentioned that `%zu' can be used in C99 for arguments of type
size_t.  Note that `%zu' can't be used directly in rarp_checkd(),
because the argument is the sum of 2 size_t's so it might not have
type size_t.  `%zu' can be used after casting the sum to size_t only
if it is known that the sum is smaller than SIZE_MAX.  The efficiency
of the printf in rarpd_checkd() is certainly not important enough to
justify this optimization.

Bruce


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