variadic function

From	Quentin Pope <qp19433@hotmail.NOSPAM.com>
Newsgroups	comp.lang.c
Subject	variadic function
Date	2011-11-05 22:32 +0000
Organization	Aioe.org NNTP Server
Message-ID	<j94dhl$6ua$1@speranza.aioe.org> (permalink)

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Consider the variadic function with the following prototype:
int foo(int num,...);
Here 'num' specifies the number of arguments, and assume that all the
arguments that should be passed to this function are of type int.
(My question has nothing to do with the definition of the function
foo, so don't bother about it.)

If I call the function as:
foo(2,3,4,5,6,7,8);/*More arguments than expected*/

Here I call foo with too many arguments than expected by its
definition.

Assuming that the prototype is visible in the scope of the function
call and the definition of function foo itself does NOT produce any
UB, please tell me if this function call produces UB or not.

I am not able to find any explicit clause from C99 which deals with
this behavior.

Though I find that:

7.19.6.1 The fprintf function
The fprintf function writes output to the stream pointed to by stream,
under control of the string pointed to by format that specifies how
subsequent arguments are converted for output. If there are
insufficient arguments for the format, the behavior is undefined. If
the format is exhausted while arguments remain, the excess arguments
are evaluated (as always) but are otherwise ignored.

This is highly specific to fprintf. I wonder if it applies to all
variadic functions.

Can I assume that the behavior of this function call is UB by
ommission?
Or am I missing something, here?

QP


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Thread

variadic function Quentin Pope <qp19433@hotmail.NOSPAM.com> - 2011-11-05 22:32 +0000
  Re: variadic function Keith Thompson <kst-u@mib.org> - 2011-11-05 15:50 -0700
    Re: variadic function Quentin Pope <qp19433@hotmail.NOSPAM.com> - 2011-11-07 17:41 +0000
  Re: variadic function James Kuyper <jameskuyper@verizon.net> - 2011-11-05 18:53 -0400
    Re: variadic function Keith Thompson <kst-u@mib.org> - 2011-11-05 16:35 -0700
      Re: variadic function Kaz Kylheku <kaz@kylheku.com> - 2011-11-06 01:36 +0000
  Re: variadic function Kaz Kylheku <kaz@kylheku.com> - 2011-11-06 01:31 +0000
  Re: variadic function Barry Schwarz <schwarzb@dqel.com> - 2011-11-06 09:45 -0800
    Re: variadic function Keith Thompson <kst-u@mib.org> - 2011-11-06 11:38 -0800
      Re: variadic function Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 23:24 -0800
        Re: variadic function Keith Thompson <kst-u@mib.org> - 2012-01-25 02:54 -0800
          Re: variadic function Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 18:22 -0800
            Re: variadic function Keith Thompson <kst-u@mib.org> - 2012-01-31 21:50 -0800
              Re: variadic function James Kuyper <jameskuyper@verizon.net> - 2012-02-01 07:55 -0500
              Re: variadic function Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-02-01 08:06 -0500
                Re: variadic function Keith Thompson <kst-u@mib.org> - 2012-02-01 11:42 -0800
              Re: variadic function Willem <willem@toad.stack.nl> - 2012-02-01 16:15 +0000
                Re: variadic function Keith Thompson <kst-u@mib.org> - 2012-02-01 11:41 -0800
              Re: variadic function Shao Miller <sha0.miller@gmail.com> - 2012-02-01 13:41 -0500
                Re: variadic function blp@cs.stanford.edu (Ben Pfaff) - 2012-02-01 10:45 -0800
              Re: variadic function Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-08 10:30 -0800
                Re: variadic function Keith Thompson <kst-u@mib.org> - 2012-03-08 13:57 -0800
                Re: variadic function Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-09 13:10 -0800
                Re: variadic function jgk@panix.com (Joe keane) - 2012-03-11 07:56 +0000
                Re: variadic function Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-11 13:01 -0700
                Re: variadic function jgk@panix.com (Joe keane) - 2012-03-12 19:04 +0000
                Re: variadic function Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-13 15:05 -0700

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