Re: Forward declarations

From	Tim Rentsch <txr@alumni.caltech.edu>
Newsgroups	comp.lang.c
Subject	Re: Forward declarations
Date	2015-11-15 13:13 -0800
Organization	A noiseless patient Spider
Message-ID	<kfntwonnez2.fsf@x-alumni2.alumni.caltech.edu> (permalink)
References	(2 earlier) <8e0d7ce4-abc9-4134-8c4b-ea3296c939ad@googlegroups.com> <n1vmpb$fi2$2@dont-email.me> <n259ls$b8$4@dont-email.me> <kfnsi48pdv4.fsf@x-alumni2.alumni.caltech.edu> <22d7dea2-f008-4297-9c6a-45a552fb12f0@googlegroups.com>

Show all headers | View raw

"Rick C. Hodgin" <rick.c.hodgin@gmail.com> writes:

> On Saturday, November 14, 2015 at 2:50:19 PM UTC-5, Tim Rentsch wrote:
>> Nick Bowler <nbowler@draconx.ca> writes:
>>
>>> It is currently impossible in C to write mutually recursive
>>> functions without declaring at least one of the functions twice.
>>
>> I wouldn't bet money on that if I were you -
>>
>>     int
>>     foo( char *s, int n, int ferrah() ){
>>         if(  *s == ' '  )  return  foo( s+1, n, ferrah );
>>         return  ferrah( s, n+1 );
>>     }
>>
>>     int
>>     bas( char *s, int n ){
>>         if(  *s == 0  )  return  n;
>>         if(  *s != ' '  )  return  bas( s+1, n );
>>         return  foo( s, n, bas );
>>     }
>
> Technically, you did declared it twice, [snip elaboration]

Each identifier in the program is declared exactly once.  The
identifier 'ferrah' is declared as a parameter as part of the
declaration (which also has an associated definition) for the
function foo().  The identifier 'bas' is declared (and defined)
as a function, and is independent of the function foo() and any
of its parameters (ie, in its declaration;  the body of bas()
refers to foo(), but that doesn't affect the declaration of the
identifier 'bas').  The declarations of 'ferrah' and 'bas' give
distinct identifier names, and so cannot be declaring the same
identifier.  The identifier names 's' and 'n' are used to declare
two identifiers each, one a parameter of foo() and the other a
parameter of bas(), but even though the names are the same there
are (for each name) two different identifiers, with each
identifier having only one declaration.

Thread

Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-10 14:20 -0800
  Re: Forward declarations jacobnavia <jacob@jacob.remcomp.fr> - 2015-11-10 23:38 +0100
    Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-10 15:00 -0800
      Re: Forward declarations Ian Collins <ian-news@hotmail.com> - 2015-11-11 12:24 +1300
        Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-10 15:53 -0800
          Re: Forward declarations gazelle@shell.xmission.com (Kenny McCormack) - 2015-11-11 00:01 +0000
          Re: Forward declarations Ian Collins <ian-news@hotmail.com> - 2015-11-11 13:46 +1300
            Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-10 21:05 -0800
    Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-11 00:21 +0000
  Re: Forward declarations Lőrinczy Zsigmond <zsiga@nospam.for.me> - 2015-11-11 10:16 +0100
    Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-11 07:19 -0800
  Re: Forward declarations David Brown <david.brown@hesbynett.no> - 2015-11-11 15:40 +0100
    Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-11 07:21 -0800
      Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-11 07:23 -0800
      Re: Forward declarations David Brown <david.brown@hesbynett.no> - 2015-11-11 16:29 +0100
        Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-11 07:31 -0800
        Re: Forward declarations Nick Bowler <nbowler@draconx.ca> - 2015-11-13 18:20 +0000
          Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-13 10:39 -0800
            Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-13 19:40 +0000
          Re: Forward declarations Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-14 11:42 -0800
            Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-14 12:32 -0800
              Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 00:15 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-14 16:34 -0800
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 01:54 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-14 18:00 -0800
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 02:13 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-14 18:26 -0800
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 02:34 +0000
                Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-15 11:11 +0000
              Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 02:36 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-14 19:25 -0800
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-14 19:37 -0800
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-14 20:11 -0800
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 10:36 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 06:16 -0800
                Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-15 14:44 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 09:41 -0800
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 18:26 +0000
                Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-15 18:42 +0000
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 18:53 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 12:58 -0800
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 12:49 -0800
                Re: Forward declarations Ian Collins <ian-news@hotmail.com> - 2015-11-16 10:01 +1300
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-15 14:54 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 09:53 -0800
                Re: Forward declarations Keith Thompson <kst-u@mib.org> - 2015-11-15 10:36 -0800
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 12:56 -0800
                Re: Forward declarations Ian Collins <ian-news@hotmail.com> - 2015-11-16 10:04 +1300
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 13:11 -0800
                Re: Forward declarations Ian Collins <ian-news@hotmail.com> - 2015-11-16 10:25 +1300
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 13:37 -0800
              Re: Forward declarations Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-15 13:13 -0800
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 13:16 -0800
                Re: Forward declarations David Brown <david.brown@hesbynett.no> - 2015-11-16 00:23 +0100
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 16:20 -0800
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-16 00:47 +0000
                Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-16 01:28 +0000
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-16 01:57 +0000
                Re: Forward declarations Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-15 21:15 -0500
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-16 11:05 +0000
                Re: Forward declarations Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-16 10:18 -0500
                Re: Forward declarations Richard Heathfield <rjh@cpax.org.uk> - 2015-11-16 06:44 +0000
                Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-16 11:26 +0000
                Re: Forward declarations David Brown <david.brown@hesbynett.no> - 2015-11-16 12:43 +0100
                Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-16 12:20 +0000
                Re: Forward declarations David Brown <david.brown@hesbynett.no> - 2015-11-16 14:38 +0100
                Re: Forward declarations Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-16 13:26 +0000
                Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-16 13:53 +0000
                Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-15 18:12 -0800
      Re: Forward declarations pa@see.signature.invalid (Pierre Asselin) - 2015-11-12 01:54 +0000
        Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-12 02:08 -0800
    Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-12 09:58 +0000
  Re: Forward declarations John Bode <jfbode1029@gmail.com> - 2015-11-17 14:46 -0800
    Re: Forward declarations "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-11-17 14:59 -0800
    Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-17 23:35 +0000
      Re: Forward declarations BartC <bc@freeuk.com> - 2015-11-17 23:40 +0000
        Re: Forward declarations Keith Thompson <kst-u@mib.org> - 2015-11-17 19:48 -0800
      Re: Forward declarations glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-18 01:04 +0000

csiph-web