Date: Fri, 05 Jan 2001 12:37:29 -0700 From: Warner Losh <imp@harmony.village.org> To: Matt Dillon <dillon@earth.backplane.com> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/usr.bin/apply apply.c Message-ID: <200101051937.f05JbTb56229@harmony.village.org> In-Reply-To: Your message of "Fri, 05 Jan 2001 11:18:23 PST." <200101051918.f05JINQ02516@earth.backplane.com> References: <200101051918.f05JINQ02516@earth.backplane.com> <jedgar@fxp.org> <200101050206.f0526rB87964@hak.lan.Awfulhak.org> <20010105162917.K85794@strontium.scientia.demon.co.uk> <20010105120633.B66833@peitho.fxp.org> <20010105184921.M85794@strontium.scientia.demon.co.uk>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <200101051918.f05JINQ02516@earth.backplane.com> Matt Dillon writes:
: Yes, but not portably. The ANSI standard tried to standardize it but
: the reality is that only snprintf()'s return value is portable. If you
: try to use the return value from other functions as a count, your code
: won't be portable. asprintf() *might* be portable too, but nothing else.
At least ANSI-99 C (well, this is the publicly available last draft
before the standard) is fairly clear about snprintf (to answer an
earlier request in this thread):
7.19.6.5 The snprintf function
Synopsis
[#1]
#include <stdio.h>
int snprintf(char * restrict s, size_t n,
const char * restrict format, ...);
Description
[#2] The snprintf function is equivalent to fprintf, except
that the output is written into an array (specified by
argument s) rather than to a stream. If n is zero, nothing
is written, and s may be a null pointer. Otherwise, output
characters beyond the n-1st are discarded rather than being
written to the array, and a null character is written at the
end of the characters actually written into the array. If
copying takes place between objects that overlap, the
behavior is undefined.
Returns
[#3] The snprintf function returns the number of characters
that would have been written had n been sufficiently large,
not counting the terminating null character, or a negative
value if an encoding error occurred. Thus, the null-
terminated output has been completely written if and only if
the returned value is nonnegative and less than n.
There is enough verbage in the C99 standard that defines the return
value of printf, et al, as the number of characters "transmitted" for
it to become portable in the coming years. However, I've never much
found a use for this information, which is likely why it has taken so
long to get it good and standardized.
Warner
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200101051937.f05JbTb56229>