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Groups > comp.lang.c > #105757

Re: va_start without the first argument?

From jt@toerring.de (Jens Thoms Toerring)
Newsgroups comp.lang.c
Subject Re: va_start without the first argument?
Date 2017-03-10 20:49 +0000
Organization Freie Universitaet Berlin
Message-ID <eighqtFfekqU1@mid.uni-berlin.de> (permalink)
References <b0f99f2b-09a3-4510-89dd-c3511fba3321@googlegroups.com>

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Thiago Adams <thiago.adams@gmail.com> wrote:
> Is it possible to create a var args function without the 
> first argument? (firstArgument in va_start)

No. You are passing an unspecified number of arguments of
unspecified types, and without the first argument the
callee has no way of finding out how man arguments it
received and what their types are. And if can'r do that
it all makes no sense.

> void F(...)
> {
>   va_list vl;
>   va_start(vl,firstArgument);

>   int i1 =va_arg(vl,int);
>   int i2 =va_arg(vl,int);

>   va_end(vl);
> }

> int main ()
> {
>   F(1, 2);
>   return 0;
> }

If you always call it with two int arguments you can as well
make F() accept only those two arguments and stop messing
around with va_arg and friends.

                           Regards, Jensa
-- 
  \   Jens Thoms Toerring  ___      jt@toerring.de
   \__________________________      http://toerring.de

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va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 11:57 -0800
  Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 12:04 -0800
  Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-10 12:32 -0800
    Re: va_start without the first argument? "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-03-10 15:51 -0500
    Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 14:36 -0800
      Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 14:53 -0800
        Re: va_start without the first argument? Robert Wessel <robertwessel2@yahoo.com> - 2017-03-10 17:14 -0600
          Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 15:37 -0800
            Re: va_start without the first argument? Robert Wessel <robertwessel2@yahoo.com> - 2017-03-10 23:12 -0600
              Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 10:29 -0700
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 11:31 -0700
                Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-13 18:40 +0000
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 12:31 -0700
            Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-11 19:53 +0100
              Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-11 19:05 +0000
                Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-11 11:56 -0800
              Re: va_start without the first argument? antispam@math.uni.wroc.pl - 2017-03-12 05:41 +0000
              Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-12 13:52 +0100
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-12 14:40 +0000
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-12 18:13 +0100
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-12 18:04 +0000
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-12 21:04 +0100
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-12 21:02 +0000
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-12 22:40 +0100
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-12 15:51 -0700
                Re: va_start without the first argument? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-03-12 16:52 -0700
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-13 00:56 +0100
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-13 09:17 -0700
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 17:54 +0000
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-13 22:12 +0100
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 22:48 +0000
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 13:46 +0100
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-14 13:37 +0000
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 15:24 +0100
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 08:25 -0700
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 17:02 +0100
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 09:45 -0700
                Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-14 09:15 -0700
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 10:02 -0700
                Re: va_start without the first argument? jt@toerring.de (Jens Thoms Toerring) - 2017-03-14 20:32 +0000
                Re: va_start without the first argument? raltbos@xs4all.nl (Richard Bos) - 2017-03-14 07:44 +0000
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 13:38 +0100
                Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-14 08:57 -0700
                Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-13 11:21 -0700
                Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-13 18:33 +0000
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-13 22:08 +0100
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-13 15:23 -0700
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 13:58 +0100
                Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-14 09:18 -0700
                Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-14 16:52 +0000
                Re: va_start without the first argument? Keith Thompson <kst-u@mib.org> - 2017-03-14 11:34 -0700
                Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-14 18:54 +0000
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 13:30 -0700
                Re: va_start without the first argument? Ike Naar <ike@iceland.freeshell.org> - 2017-03-15 21:55 +0000
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-15 15:16 -0700
                Re: va_start without the first argument? Philip Lantz <prl@canterey.us> - 2017-03-23 21:04 -0700
                Re: va_start without the first argument? David Brown <david.brown@hesbynett.no> - 2017-03-14 21:48 +0100
                Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-14 14:01 +0000
                Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-14 07:42 -0700
                Re: va_start without the first argument? scott@slp53.sl.home (Scott Lurndal) - 2017-03-14 12:38 +0000
                Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-13 01:11 +0100
                Re: va_start without the first argument? Ian Collins <ian-news@hotmail.com> - 2017-03-13 15:43 +1300
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 10:36 +0000
                Re: va_start without the first argument? Ian Collins <ian-news@hotmail.com> - 2017-03-14 07:33 +1300
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 19:00 +0000
                Re: va_start without the first argument? Ian Collins <ian-news@hotmail.com> - 2017-03-14 08:05 +1300
                Re: va_start without the first argument? BartC <bc@freeuk.com> - 2017-03-13 23:10 +0000
                Re: va_start without the first argument? Ian Collins <ian-news@hotmail.com> - 2017-03-14 17:38 +1300
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-14 05:48 -0700
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 12:12 -0700
                Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-12 19:39 +0100
  Re: va_start without the first argument? jt@toerring.de (Jens Thoms Toerring) - 2017-03-10 20:49 +0000
    Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-10 14:41 -0800
      Re: va_start without the first argument? John Bode <jfbode1029@gmail.com> - 2017-03-10 16:05 -0800
        Re: va_start without the first argument? jacob navia <jacob@jacob.remcomp.fr> - 2017-03-11 21:47 +0100
          Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-11 13:07 -0800
            Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-11 22:24 +0100
              Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 05:44 -0700
                Re: va_start without the first argument? Jerry Stuckle <jstucklex@attglobal.net> - 2017-03-13 08:59 -0400
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 06:17 -0700
                Re: va_start without the first argument? Jerry Stuckle <jstucklex@attglobal.net> - 2017-03-13 13:27 -0400
                Re: va_start without the first argument? Jerry Stuckle <jstucklex@attglobal.net> - 2017-03-13 13:30 -0400
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 11:00 -0700
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 10:34 -0700
          Re: va_start without the first argument? antispam@math.uni.wroc.pl - 2017-03-12 06:00 +0000
          Re: va_start without the first argument? gordonb.gas5o@burditt.org (Gordon Burditt) - 2017-03-17 09:46 -0500
            Re: va_start without the first argument? supercat@casperkitty.com - 2017-03-17 09:07 -0700
        Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 05:39 -0700
          Re: va_start without the first argument? John Bode <jfbode1029@gmail.com> - 2017-03-13 11:40 -0700
            Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 12:01 -0700
              Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-13 23:17 +0100
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 16:15 -0700
                Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-14 00:26 +0100
                Re: va_start without the first argument? kikiins@gmail.com - 2017-03-13 16:51 -0700
                Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-14 01:12 +0100
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 18:24 -0700
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-13 18:57 -0700
                Re: va_start without the first argument? raltbos@xs4all.nl (Richard Bos) - 2017-03-14 07:59 +0000
                Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-14 06:45 -0700
                Re: va_start without the first argument? Robert Wessel <robertwessel2@yahoo.com> - 2017-03-13 18:20 -0500
                Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-14 00:31 +0100
    Re: va_start without the first argument? raltbos@xs4all.nl (Richard Bos) - 2017-03-13 16:51 +0000
  Re: va_start without the first argument? jacobnavia <jacob@jacob.remcomp.fr> - 2017-03-11 19:29 +0100
  Re: va_start without the first argument? Siri Cruise <chine.bleu@yahoo.com> - 2017-03-11 12:12 -0800
  Re: va_start without the first argument? luser droog <luser.droog@gmail.com> - 2017-03-13 05:37 -0700
    Re: va_start without the first argument? luser droog <luser.droog@gmail.com> - 2017-03-15 11:45 -0700
      Re: va_start without the first argument? Thiago Adams <thiago.adams@gmail.com> - 2017-03-15 13:39 -0700

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