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| Message-ID | <pamfe8-4ig.ln1@wilbur.25thandClement.com> (permalink) |
|---|---|
| From | William Ahern <william@wilbur.25thandClement.com> |
| Subject | Re: PRI* considered harmful |
| Newsgroups | comp.std.c |
| References | <87mxgqhk3x.fsf@once.weird.com> |
| Date | 2011-07-06 20:38 -0700 |
Greg A. Woods <woods@robohack.org> wrote:
> I've been scratching my head over this ever since I first tried to
> actually use the PRI* macros in real-world code, and a recent discussion
> about what to do w.r.t. some systems are increasing time_t to be 64 bits
> caused me to go searching the Internets further, but to no avail.
> Everyone is inventing their own hokey incompatible schemes and nobody is
> really benefiting from any improvement in the standard.
<snip>
> I've also seen it suggested that _every_ non-base-integer type _always_
> be cast to [u]intmax_t and printed using PRI[ud]MAX:
> printf("%" PRIuMAX, (uintmax_t) uival);
> printf("%" PRIdMAX, (intmax_t) t); /* for signed values */
> Now we're safe for every possible underlying type of any typedef name,
> home baked, or standardised.
time_t could be also be double, not just an integer. This is why difftime()
exists. Note that it returns a double. PRI-type macros can't really solve
the problem because of the different format specifications between double
and integer types.
The proper answer is strftime().
The real problem is converting a time_t to struct tm because of the use of
globals in gmtime() and localtime(). As far as I can tell this problem isn't
directly addressed yet in the latest C1x draft I have locally,
notwithstanding the Annex K extension library. Visual Studio implements
parts of Annex K, including gmtime_s() and localtime_s(). POSIX defines
gmtime_r() and localtime_r(), from which the Annex K routines are presumably
drawn.
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PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-06 19:58 -0700
Re: PRI* considered harmful William Ahern <william@wilbur.25thandClement.com> - 2011-07-06 20:38 -0700
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-06 22:26 -0700
Re: PRI* considered harmful Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-07 08:52 +0200
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-07 14:11 -0700
Re: PRI* considered harmful Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-08 11:58 +0200
Re: PRI* considered harmful lawrence.jones@siemens.com - 2011-07-07 17:58 -0400
Re: PRI* considered harmful Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-08 12:02 +0200
Re: PRI* considered harmful lawrence.jones@siemens.com - 2011-07-07 17:57 -0400
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-07 15:42 -0700
Re: PRI* considered harmful lawrence.jones@siemens.com - 2011-07-08 08:56 -0400
Re: PRI* considered harmful James Kuyper <jameskuyper@verizon.net> - 2011-07-07 06:36 -0400
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-07 12:59 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-07 14:12 -0700
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-07 15:49 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-07 16:46 -0700
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-07 18:26 -0700
Re: PRI* considered harmful James Kuyper <jameskuyper@verizon.net> - 2011-07-07 22:35 -0400
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-07 20:58 -0700
Re: PRI* considered harmful Wojtek Lerch <wojtek_l@yahoo.ca> - 2011-07-08 00:28 -0400
Re: PRI* considered harmful James Kuyper <jameskuyper@verizon.net> - 2011-07-08 07:41 -0400
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-08 23:05 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 00:50 -0700
Re: [incorrectly implementd] PRI* considered harmful James Kuyper <jameskuyper@verizon.net> - 2011-07-09 06:38 -0400
Re: PRI* considered harmful Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2011-07-09 21:07 +0200
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-08 09:52 -0700
Re: PRI* considered harmful Richard Kettlewell <rjk@greenend.org.uk> - 2011-07-08 11:45 +0100
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-08 23:14 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 00:47 -0700
Re: PRI* considered harmful Richard Kettlewell <rjk@greenend.org.uk> - 2011-07-09 10:51 +0100
Re: PRI* considered harmful James Kuyper <jameskuyper@verizon.net> - 2011-07-09 06:43 -0400
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-08 09:49 -0700
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-08 23:24 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 00:45 -0700
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-09 16:18 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 18:57 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-13 09:37 -0700
Re: PRI* considered harmful James Kuyper <jameskuyper@verizon.net> - 2011-07-09 06:46 -0400
Re: PRI* considered harmful Harald van Dijk <truedfx@gmail.com> - 2011-07-09 08:09 -0700
Re: PRI* considered harmful Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-07-11 16:00 +0300
Re: PRI* considered harmful Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2011-07-09 20:59 +0200
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 12:22 -0700
Re: PRI* considered harmful Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2011-07-09 21:32 +0200
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 12:54 -0700
Re: PRI* considered harmful Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-09 23:39 +0200
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-09 16:56 -0700
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-09 16:52 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 18:53 -0700
Re: PRI* considered harmful Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-10 14:12 +0200
Re: PRI* considered harmful Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-11 20:22 +0200
Re: PRI* considered harmful Jens Gustedt <Jens.Gustedt@loria.fr> - 2011-07-10 13:57 +0200
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-09 16:49 -0700
Re: PRI* considered harmful Jens Schweikhardt <usenet@schweikhardt.net> - 2011-07-19 19:28 +0000
Re: PRI* considered harmful Tim Rentsch <txr@alumni.caltech.edu> - 2011-07-07 14:13 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 01:04 -0700
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-09 17:23 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-09 19:03 -0700
Re: PRI* considered harmful Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-11 20:40 +0200
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-11 11:56 -0700
Re: PRI* considered harmful Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-11 21:40 +0200
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-11 13:16 -0700
Re: PRI* considered harmful Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-07-11 23:29 +0200
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-11 14:46 -0700
Re: PRI* considered harmful "Greg A. Woods" <woods@robohack.org> - 2011-07-12 22:18 -0700
Re: PRI* considered harmful Keith Thompson <kst-u@mib.org> - 2011-07-13 09:00 -0700
Re: PRI* considered harmful Richard Kettlewell <rjk@greenend.org.uk> - 2011-07-09 20:30 +0100
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