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

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jononanon@googlemail.com writes:
> Hi there!
>
> Check this out -> the following code always works:
>
> printf("%d %d %d", (char)'\1', (short)2, 3);
> // prints: 1 2 3
>
> So a conversion specifier of %d works with type int, or "SMALLER"
> integer-types (short or char) !!!
>
> Why does this work??
> Is my explanation correct? 
[...]

N1570 (C11 draft) 6.5.2.2p7:

    The ellipsis notation in a function prototype declarator causes
    argument type conversion to stop after the last declared
    parameter. The default argument promotions are performed on
    trailing arguments.

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.

-- 
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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