Subject: Re: [OT] u_int*_t vs. uint*_t - which to use?
To: NetBSD Users <email@example.com>
From: David Laight <David@l8s.co.uk>
Date: 01/19/2002 20:15:25
> I apologize in advance if this is OT, but I've been scouring the 'Net for
> some time and still can't find the answer. I have been using "intX_t" and
> "u_intX_t" for years in my applications because I believed it was the
> portable thing to do according to POSIX 1003.1. I have had no problems
> between NetBSD, Linux and HP-UX. Recently, I discovered that these types
> are not defined anywhere on SunOS 5.6. Instead, there is "intX_t" (yes,
> the same) and "uintX_t". These are defined via <inttypes.h>. Now I see
> that NetBSD, Linux and HP-UX define these as well. Am I incorrect to use
> the (apparently) old-style "u_intX_t"? It seems these newer types (via
> <inttypes.h>) are UNIX-98. I would like to know if this supercedes the
> POSIX types.
We had some discussions about this at the last X/Open Xnet meeting I
was at. We were trying to guess what the C standard would say,
unfortunately that standards group was failing to make a decision.
I don't know what has happened in the intervening few years, but the
following comment from my Solaris 8 system it probably correct.
(Sun were tracking the C standard, and their XNET rep. had been briefed)
* This file, <sys/int_types.h>, is part of the Sun Microsystems implementation
* of <inttypes.h> as proposed in the ISO/JTC1/SC22/WG14 C committee's working
* draft for the revision of the current ISO C standard, ISO/IEC 9899:1990
* Programming language - C.
* Programs/Modules should not directly include this file. Access to the
* types defined in this file should be through the inclusion of one of the
* following files:
* <sys/types.h> Provides only the "_t" types defined in this
* file which is a subset of the contents of
* <inttypes.h>. (This can be appropriate for
* all programs/modules except those claiming
* ANSI-C conformance.)
* <sys/inttypes.h> Provides the Kernel and Driver appropriate
* components of <inttypes.h>.
* <inttypes.h> For use by applications.
* See these files for more details.
* Use at your own risk. As of February 1996, the committee is squarely
* behind the fixed sized types; the "least" and "fast" types are still being
* discussed. The probability that the "fast" types may be removed before
* the standard is finalized is high enough that they are not currently
* implemented. The unimplemented "fast" types are of the form
* [u]int_fast[0-9]*_t and [u]intfast_t.
The file then goes on to define:
[u]int[n]*_t, [u]intmax_t, [u]intptr_t and [u]int_least[n]_t
No hint of a u_xxx type anywhere.
Hope that muddies things...