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Groups > comp.lang.c > #64971

Re: printf format specifier changes

From Phil Carmody <pc+usenet@asdf.org>
Newsgroups comp.lang.c
Subject Re: printf format specifier changes
Date 2015-07-09 11:12 +0300
Organization A noiseless patient Spider
Message-ID <87a8v5da0m.fsf@bazspaz.fatphil.org> (permalink)
References <d9147e9f-77b1-435a-b037-24041fd6974a@googlegroups.com> <mnebi4$p4v$1@dont-email.me> <mni35p$efa$2@dont-email.me> <lnwpyb9uy4.fsf@kst-u.example.com>

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Keith Thompson <kst-u@mib.org> writes:
> Les Cargill <lcargill99@comcast.com> writes:
> > Bartc wrote:
> >> On 06/07/2015 17:04, Rick C. Hodgin wrote:
> >>> In 2015, what suggestions would you have for changing anything about
> >>> the format specifiers used in the printf functions?  Leave them as
> >>> they are?  Or change this or that about them?
> >>
> >> In 2015, the whole notion of having to tell a compiler what it already
> >> knows - the type of the values it's printing - is outdated.
> >>
> >
> > No, it is not.
> >
> > Example 1:
> >
> > char *s = something();
> >
> > printf(":%s: 0x%08x\n",s,(int)s);
> >
> > Every. Single. Attempt. To improve on this. Fails. Repeatedly.
> 
> %x requires an unsigned int, not an int.  But I would write that as:
> 
>     printf(":%s: %p\n", s, (void*)s);
> 
> (It can be argued that the cast is not needed in this case, but it's
> easier to be consisten.)
> 
> [...]

In that "..." was "Serialization Is Hard.".

%p is not particularly good serialisation, as its output is
implementation defined. Someone else parsing those logs may
not recognise the format being used and either only partially
parse the printed value (as it didn't expect so much), or even
refuse to parse it (as it expected more).

Phil
-- 
A well regulated militia, being necessary to the security of a free state,
the right of the people to keep and bear arms, shall be well regulated.

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printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-06 09:04 -0700
  Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-06 17:50 +0100
    Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-06 11:34 -0700
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-06 19:47 +0100
        Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-06 19:53 +0100
          Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-06 11:57 -0700
      Re: printf format specifier changes "James Harris" <james.harris.1@gmail.com> - 2015-09-06 10:53 +0100
        Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-06 04:21 -0700
          Re: printf format specifier changes "James Harris" <james.harris.1@gmail.com> - 2015-09-07 10:40 +0100
            Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-07 03:07 -0700
              Re: printf format specifier changes "James Harris" <james.harris.1@gmail.com> - 2015-09-07 15:09 +0100
            Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-07 12:03 +0100
              Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-07 12:46 +0100
                Re: printf format specifier changes "James Harris" <james.harris.1@gmail.com> - 2015-09-07 15:24 +0100
              Re: printf format specifier changes "James Harris" <james.harris.1@gmail.com> - 2015-09-07 15:16 +0100
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-07 17:09 +0100
                Re: printf format specifier changes "James Harris" <james.harris.1@gmail.com> - 2015-09-07 17:47 +0100
                Re: printf format specifier changes Richard Damon <Richard@Damon-Family.org> - 2015-09-07 13:29 -0400
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-08 12:17 +0100
                Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-09-08 10:13 -0500
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-08 17:09 +0100
                Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-09-08 10:08 -0700
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-08 19:11 +0100
                Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-09-08 12:24 -0700
                Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-09-08 14:56 -0500
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-08 22:18 +0100
                Re: printf format specifier changes Ian Collins <ian-news@hotmail.com> - 2015-09-09 09:29 +1200
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-08 22:58 +0100
                Re: printf format specifier changes Ian Collins <ian-news@hotmail.com> - 2015-09-09 10:32 +1200
                Re: printf format specifier changes supercat@casperkitty.com - 2015-09-08 15:57 -0700
                Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-09-08 15:12 -0700
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-08 23:45 +0100
                Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-09-08 16:36 -0700
                Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-09-08 19:17 -0500
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-09 09:56 +0100
                Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-09-09 11:33 -0700
                Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-09-09 20:35 +0100
                Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-09-08 14:51 -0500
                Re: printf format specifier changes David Brown <david.brown@hesbynett.no> - 2015-09-08 22:41 +0200
              Re: printf format specifier changes Richard Damon <Richard@Damon-Family.org> - 2015-09-07 12:03 -0400
          Re: printf format specifier changes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-10 06:33 +0000
            Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-10 02:38 -0700
        Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-06 13:41 +0100
          Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-09-07 00:23 -0500
          Re: printf format specifier changes "James Harris" <james.harris.1@gmail.com> - 2015-09-07 11:31 +0100
            Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-07 03:54 -0700
    Re: printf format specifier changes Richard Heathfield <rjh@cpax.org.uk> - 2015-07-06 19:44 +0100
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-06 22:14 +0100
        Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-07-06 22:43 -0500
        Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-06 23:01 -0700
          Re: printf format specifier changes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-07 06:43 +0000
          Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-09 10:52 +0300
            Re: printf format specifier changes Richard Heathfield <rjh@cpax.org.uk> - 2015-07-09 09:26 +0100
              Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-12 12:56 +0300
                Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-12 06:12 -0700
        Re: printf format specifier changes Rosario19 <Ros@invalid.invalid> - 2015-07-07 10:22 +0200
          Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-07 10:10 +0100
      Re: printf format specifier changes Philip Lantz <prl@canterey.us> - 2015-07-07 00:54 -0700
    Re: printf format specifier changes Nobody <nobody@nowhere.invalid> - 2015-07-07 15:08 +0100
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-07 16:12 +0100
        Re: printf format specifier changes raltbos@xs4all.nl (Richard Bos) - 2015-07-09 10:34 +0000
          Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-09 12:25 +0100
            Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-12 13:02 +0300
              Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-12 11:23 +0100
    Re: printf format specifier changes <william@wilbur.25thandClement.com> - 2015-07-07 11:50 -0700
      Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-07 12:14 -0700
    Re: printf format specifier changes Les Cargill <lcargill99@comcast.com> - 2015-07-07 21:52 -0500
      Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-07 20:42 -0700
        Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-09 11:12 +0300
          Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-09 05:03 -0700
            Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 13:10 -0500
          Re: printf format specifier changes James Kuyper <jameskuyper@verizon.net> - 2015-07-09 08:58 -0400
          Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-09 08:10 -0700
            Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-12 12:58 +0300
              Re: printf format specifier changes James Kuyper <jameskuyper@verizon.net> - 2015-07-12 12:57 -0400
              Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-12 11:14 -0700
                Re: printf format specifier changes gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-12 18:26 +0000
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-08 13:09 +0100
      Re: printf format specifier changes James Kuyper <jameskuyper@verizon.net> - 2015-07-08 08:10 -0400
        Re: printf format specifier changes Les Cargill <lcargill99@comcast.com> - 2015-07-08 08:12 -0500
          Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-08 08:38 -0700
          Re: printf format specifier changes James Kuyper <jameskuyper@verizon.net> - 2015-07-08 12:00 -0400
            Re: printf format specifier changes Les Cargill <lcargill99@comcast.com> - 2015-07-08 17:20 -0500
      Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-09 11:08 +0300
    Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-08 20:30 +0300
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-08 18:56 +0100
        Re: printf format specifier changes gordonb.lmwiv@burditt.org (Gordon Burditt) - 2015-07-09 11:09 -0500
          Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 14:05 -0500
      Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-08 11:27 -0700
        Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-08 15:07 -0500
  Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-06 23:39 -0500
    Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-07 10:19 +0100
      Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 07:57 -0500
        Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-07 14:15 +0100
          Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-07 14:46 +0100
          Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 09:37 -0500
        Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-09 11:24 +0300
          Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 09:55 -0500
            Re: printf format specifier changes <william@wilbur.25thandClement.com> - 2015-07-09 11:53 -0700
              Re: printf format specifier changes <william@wilbur.25thandClement.com> - 2015-07-09 13:48 -0700
              Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 17:01 -0500
    Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-07 10:59 +0100
      Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 07:48 -0500
        Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-07 14:30 +0100
          Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 10:05 -0500
            Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-07 23:16 +0100
              Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 20:29 -0500
              Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-08 00:43 -0700
              Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-07-09 02:29 -0500
                Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-09 10:34 +0100
                Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 09:35 -0500
          Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-07 08:37 -0700
            Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-07 08:45 -0700
            Re: printf format specifier changes supercat@casperkitty.com - 2015-09-07 08:29 -0700
          Re: printf format specifier changes <william@wilbur.25thandClement.com> - 2015-07-07 12:12 -0700
  Re: printf format specifier changes pooja deshpande <namitadeshpande25@gmail.com> - 2015-07-09 09:29 -0700
    Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 09:34 -0700
      Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 09:59 -0700
        Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-09 22:33 +0100
          Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-09 15:17 -0700
            Re: printf format specifier changes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-10 00:30 +0000
              Re: printf format specifier changes Reinhardt Behm <rbehm@hushmail.com> - 2015-07-10 09:17 +0800
      Re: printf format specifier changes David Kleinecke <dkleinecke@gmail.com> - 2015-07-09 10:02 -0700
        Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 10:19 -0700
      Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-09 21:50 +0100
        Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-09 15:05 -0700
          Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 15:09 -0700
          Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-10 00:28 +0100
            Re: printf format specifier changes raltbos@xs4all.nl (Richard Bos) - 2015-07-13 20:39 +0000
        Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 15:07 -0700
          Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-09 23:16 +0100
            Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 15:25 -0700

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