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Re: why printf("%d", arg) works with arg of type int, short, char

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<william@wilbur.25thandClement.com> writes:
> Keith Thompson <kst-u@mib.org> wrote:
[...]
>> The default argument promotions convert float to double, and any
>> integer type narrower than int is convert to int if int can represent
>> all the values of the type, otherwise to unsigned int.  (The latter
>> avoids overflow when an unsigned short value is promoted and short
>> and int are the same size.)
>> 
>> That's why, among other things, there are no specific printf formats
>> for float or short.
>
> There's the `h' length modifier for shorts. Also `hh' for chars.

Good point, I momentarily forgot about those.

"%hd" still requires an int argument (possibly promoted from short),
but the value is *converted* to short before printing.  I'm actually
not sure what it's good for.  If the argument is already in the
range of type short, then it behaves identically to "%d"; if it's
outside that range, the result is implementation-defined (or, at
least in principle, it can raise an implementation-defined signal).

At least for "%hu" or "%hx", the behavior of the conversion is well
defined, but the behavior is still identical to "%u" or "%x" if the
argument is of type unsigned short.  But I'm really not sure why the "h"
and "hh" length modifiers were added to the language.  ("h" was added in
ANSI C89, "hh" in C99.)

[temporarily posting through aioe.org due to problems with
eternal-september.org]

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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why printf("%d", arg) works with arg of type int, short, char jononanon@googlemail.com - 2014-03-01 01:29 -0800
  Re: why printf("%d", arg) works with arg of type int, short, char jononanon@googlemail.com - 2014-03-01 01:42 -0800
    Re: why printf("%d", arg) works with arg of type int, short, char jononanon@googlemail.com - 2014-03-01 01:54 -0800
      Re: why printf("%d", arg) works with arg of type int, short, char Barry Schwarz <schwarzb@dqel.com> - 2014-03-01 07:21 -0800
        Re: why printf("%d", arg) works with arg of type int, short, char gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-01 15:51 +0000
          Re: why printf("%d", arg) works with arg of type int, short, char Richard <rgrdev_@gmail.com> - 2014-03-01 17:50 +0100
            Re: why printf("%d", arg) works with arg of type int, short, char gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-01 18:36 +0000
  Re: why printf("%d", arg) works with arg of type int, short, char Melzzzzz <mel@zzzzz.invalid> - 2014-03-01 11:22 +0100
    Re: why printf("%d", arg) works with arg of type int, short, char jononanon@googlemail.com - 2014-03-01 02:39 -0800
    Re: why printf("%d", arg) works with arg of type int, short, char Keith Thompson <kst-u@mib.org> - 2014-03-01 19:44 -0800
  Re: why printf("%d", arg) works with arg of type int, short, char Keith Thompson <kst-u@mib.org> - 2014-03-01 02:34 -0800
    Re: why printf("%d", arg) works with arg of type int, short, char jononanon@googlemail.com - 2014-03-01 02:49 -0800
      Re: why printf("%d", arg) works with arg of type int, short, char James Kuyper <jameskuyper@verizon.net> - 2014-03-01 09:10 -0500
    Re: why printf("%d", arg) works with arg of type int, short, char <william@wilbur.25thandClement.com> - 2014-03-01 15:38 -0800
      Re: why printf("%d", arg) works with arg of type int, short, char Keith Thompson <kst-u@mib.org> - 2014-03-01 19:47 -0800
        Re: why printf("%d", arg) works with arg of type int, short, char <william@wilbur.25thandClement.com> - 2014-03-01 21:12 -0800
        Re: why printf("%d", arg) works with arg of type int, short, char Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2014-03-02 07:47 -0700
          Re: why printf("%d", arg) works with arg of type int, short, char Kaz Kylheku <kaz@kylheku.com> - 2014-03-02 20:53 +0000
            Re: why printf("%d", arg) works with arg of type int, short, char jgk@panix.com (Joe keane) - 2014-03-04 00:23 +0000
              Re: why printf("%d", arg) works with arg of type int, short, char Kaz Kylheku <kaz@kylheku.com> - 2014-03-04 00:33 +0000
                Re: why printf("%d", arg) works with arg of type int, short, char glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-04 00:45 +0000
                Re: why printf("%d", arg) works with arg of type int, short, char jgk@panix.com (Joe keane) - 2014-03-05 04:07 +0000
                Re: why printf("%d", arg) works with arg of type int, short, char Barry Schwarz <schwarzb@dqel.com> - 2014-03-05 10:07 -0800
  Re: why printf("%d", arg) works with arg of type int, short, char "BartC" <bc@freeuk.com> - 2014-03-01 11:12 +0000
    Re: why printf("%d", arg) works with arg of type int, short, char Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-03-01 10:54 -0500
      Re: why printf("%d", arg) works with arg of type int, short, char glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-01 18:55 +0000

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