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Re: Making C more beautiful by not using macros with arguments

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Bartc <bc@freeuk.com> writes:
[...]
> As an example of the quirks, take this simple program:
>
>  int main(void) {}
>
> How many people know that it can also be written like this:
>
>  int (main(void)) {}
>
> (with the extra parentheses)? At least one C compiler doesn't!


I didn't know that, but I verified it by compiling with gcc and checking
the syntax in the standard.

Which compiler?

Incidentally, cdecl recognizes int (main(void)) -- and any compiler that
doesn't is non-conforming.

> While the prototype for a function 'g', taking parameter type 'h', and
> returning type 'f', can be written as:
>
>  f(g(h));
>
> Which happens to look exactly like a couple of nested function calls!
> (This means it's not possible to write a simple syntax translator for
> C.)

The difference is that f and h are type names, which are syntactically
distinct from identifiers.

This:

    int(g(int));

is valid, but is more clearly written as

    int g(int);

Parentheses are permitted in declarators for the same reason they're
allowed in expressions: to specify grouping and improve clarity.  C's
declaration syntax is peculiar enough that the result can be confusing.

In this case, int is a keyword, not an identifier, so there's no real
ambiguity.  If you use a typedef name:

    typedef int foo;
    foo(g(foo));
    // or foo g(foo);

it *seems* more ambiguous, but it isn't really.  Typedefs were added to
the language relatively late (I don't remember whether K&R1 had them),
and they caused some syntactic problems.  A typedef declaration
effectively creates a new keyword, but only within the scope of the
declaration -- except that the identifier can be redeclared in an inner
scope.  This makes it impossible to parse C without feedback from the
symbol table.

-- 
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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Thread

Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-05-29 10:36 -0700
  Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-29 19:04 +0100
    Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-05-30 07:30 -0700
      Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-30 15:51 +0100
  Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-29 19:26 +0100
    Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-05-30 07:38 -0700
      Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-30 21:44 +0100
        Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-30 23:58 +0100
          Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-31 00:27 +0100
            Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-31 10:21 +0100
              Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-31 11:00 +0100
                Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-05-31 09:45 -0700
                Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-31 18:20 +0100
                Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-05-31 13:04 -0700
                Re: Making C more beautiful by not using macros with arguments Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-05-31 16:11 -0400
                Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-31 21:48 +0100
                Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-05-31 14:22 -0700
                Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-06-01 11:33 -0700
                Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-31 20:37 +0100
                Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-05-31 14:18 -0700
                Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-31 22:44 +0100
                Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-31 23:16 +0100
                Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-06-01 11:58 -0700
                Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-02 01:14 +0100
                Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-06-02 10:31 +0100
                Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-02 11:06 +0100
                Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-06-02 11:39 +0100
                Re: Making C more beautiful by not using macros with arguments "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-06-02 04:02 -0700
                Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-02 12:24 +0100
                Re: Making C more beautiful by not using macros with arguments Noob <root@127.0.0.1> - 2015-06-02 15:41 +0200
                Re: Making C more beautiful by not using macros with arguments Richard Heathfield <rjh@cpax.org.uk> - 2015-06-02 15:00 +0100
                Re: Trolls/Cranks/Kooks Noob <root@127.0.0.1> - 2015-06-02 16:41 +0200
                Re: Trolls/Cranks/Kooks Richard Heathfield <rjh@cpax.org.uk> - 2015-06-02 15:56 +0100
                Re: Trolls/Cranks/Kooks Noob <root@127.0.0.1> - 2015-06-02 17:09 +0200
                Re: Trolls/Cranks/Kooks Richard Heathfield <rjh@cpax.org.uk> - 2015-06-02 16:17 +0100
                Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-02 15:58 +0100
                Re: Making C more beautiful by not using macros with arguments Dr Nick <nospam-4@temporary-address.org.uk> - 2015-06-02 19:32 +0100
                Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-06-02 11:00 -0700
                Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-02 20:13 +0100
      Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-05-30 15:17 -0700
        Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-05-31 09:12 -0700
          Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-05-31 13:29 -0700
      Re: Making C more beautiful by not using macros with arguments David Brown <david.brown@hesbynett.no> - 2015-05-31 17:28 +0200
  Re: Making C more beautiful by not using macros with arguments Morris Dovey <mrdovey@iedu.com> - 2015-05-29 13:35 -0500
  Re: Making C more beautiful by not using macros with arguments "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-05-29 13:19 -0700
    Re: Making C more beautiful by not using macros with arguments "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-05-29 13:25 -0700
  Re: Making C more beautiful by not using macros with arguments Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-05-29 14:23 -0600
  Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-05-29 14:16 -0700
    Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-05-30 07:46 -0700
      Re: Making C more beautiful by not using macros with arguments Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-05-30 18:28 -0400
        Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-05-31 09:27 -0700
          Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-31 17:59 +0100
            Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-06-01 11:24 -0700
              Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-06-01 12:15 -0700
                Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-06-01 12:21 -0700
                Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-06-01 12:53 -0700
          Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-05-31 13:36 -0700
          Re: Making C more beautiful by not using macros with arguments David Brown <david.brown@hesbynett.no> - 2015-05-31 23:26 +0200
            Re: Making C more beautiful by not using macros with arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-31 23:09 +0100
            Re: Making C more beautiful by not using macros with arguments luser droog <luser.droog@gmail.com> - 2015-05-31 15:51 -0700
              Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-06-01 12:08 -0700
        Re: Making C more beautiful by not using macros with arguments James Kuyper <jameskuyper@verizon.net> - 2015-06-01 12:38 -0400
          Re: Making C more beautiful by not using macros with arguments Dr Nick <nospam-4@temporary-address.org.uk> - 2015-06-01 19:20 +0100
          Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-06-01 12:18 -0700
      Re: Making C more beautiful by not using macros with arguments Keith Thompson <kst-u@mib.org> - 2015-05-30 15:43 -0700
        Re: Making C more beautiful by not using macros with arguments David Kleinecke <dkleinecke@gmail.com> - 2015-05-31 09:32 -0700
  Re: Making C more beautiful by not using macros with arguments Les Cargill <lcargill99@comcast.com> - 2015-05-29 22:07 -0500
  Making C more beautiful by not using macros with arguments rick.c.hodgin@gmail.com - 2015-05-30 09:22 -0700
    Re: Making C more beautiful by not using macros with arguments Morris Dovey <mrdovey@iedu.com> - 2015-05-30 14:22 -0500
      Re: Making C more beautiful by not using macros with arguments Bartc <bc@freeuk.com> - 2015-05-30 21:29 +0100
        Re: Making C more beautiful by not using macros with arguments Morris Dovey <mrdovey@iedu.com> - 2015-05-30 22:15 -0500
          Re: Making C more beautiful by not using macros with arguments Morris Dovey <mrdovey@iedu.com> - 2015-06-08 20:16 -0500
  Re: Making C more beautiful by not using macros with arguments David Brown <david.brown@hesbynett.no> - 2015-05-31 17:32 +0200
  Re: Making C more beautiful by not using macros with arguments Richard Heathfield <rjh@cpax.org.uk> - 2015-06-01 22:51 +0100

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