Re: better atoi

From	BartC <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: better atoi
Date	2017-02-12 19:18 +0000
Organization	A noiseless patient Spider
Message-ID	<o7qc9t$nj9$1@dont-email.me> (permalink)
References	(12 earlier) <649395f0-f6fa-4779-b563-71527b7e677c@googlegroups.com> <a0b5a4f1-4e7b-41d6-88b8-d63a0de85a4c@googlegroups.com> <491bde1c-4dc9-4c49-ab7c-496eb64f4362@googlegroups.com> <o7q9kb$dcr$1@dont-email.me> <877f4vw83z.fsf@bsb.me.uk>

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On 12/02/2017 18:56, Ben Bacarisse wrote:
> BartC <bc@freeuk.com> writes:
> <snip>
>> ...  but C presumably must have been
>> perfect because few of the troublesome details has been touched for
>> decades!
>
> More accurately: C has been successful for decades because few of the
> details have been touched.
>
> <snip>
>>   int (*abc)[10];
>>
>> This follows the recursive definition in the Standard
>> beautifully. Except the implementation of it doesn't match the
>> grammar: that "*" pointer somewhere has to find its way outside the
>> brackets,
>
> It matches the grammar just fine (as you say).  If your implementation
> does does not reflect the parse, that's not C's fault.  The * must be
> inside the brackets or the type would an array type.

The type in the example can be expressed definitively in English as the 
left-to-right sequence:

   Pointer-Array-Int

If "*" is Pointer, abc is Int, and [10] is Array, then the declaration 
is arranged like this:

   (Pointer-Int)-Array

I can just about get the Array part to be moved in between the other 
two, but it's an ugly hack.

However, if I change abc to Pointer-Array-Int, "*" to "Deref", and 
"[10]" to index, then the declaration becomes:

  (Deref-Pointer-Array-Int)-Index

Now, Deref-Pointer cancel, leaving (Array-Int)Index. Array-Index cancel, 
leaving Int, the type you can get when you evaluate abc[i]. This is the 
famous Declaration-follows-use, the reason type-decls are as they are.

But clearly that is no use at all in parsing those type-decls. For a 
start, you don't know abc is Pointer-Array-Int, as that's what you're 
trying to establish! And you don't want to end up with Int, but with 
Pointer-Array-Int.

-- 
Bartc

Thread

better atoi fir <profesor.fir@gmail.com> - 2017-02-10 12:24 -0800
  Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-10 12:35 -0800
  Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 14:48 -0700
    Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-10 14:12 -0800
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 22:36 -0700
        Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-11 01:07 -0800
          Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 10:10 -0700
            Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-11 09:26 -0800
              Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 15:36 -0700
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 00:18 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 00:31 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 03:47 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 04:22 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 06:08 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 06:13 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 07:31 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 08:02 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 08:08 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 08:17 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 08:23 -0800
                Re: better atoi Robert Latest <boblatest@yahoo.com> - 2017-02-19 11:11 +0000
            Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-11 17:33 +0000
              Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 15:35 -0700
                Re: better atoi "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-11 17:52 -0500
                Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 18:53 -0700
    Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-10 22:50 +0000
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 21:59 -0700
        Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-11 12:08 +0000
          Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 09:39 -0700
            Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-11 17:26 +0000
              Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 15:30 -0700
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-11 22:58 +0000
                Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 18:48 -0700
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-12 02:16 +0000
                Re: better atoi "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-12 09:57 -0500
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 07:27 -0800
                Re: better atoi jameskuyper@verizon.net - 2017-02-12 08:44 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 09:15 -0800
                Re: better atoi Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-12 09:44 -0800
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-12 18:32 +0000
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-12 18:56 +0000
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-12 19:18 +0000
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-13 00:16 +0000
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-13 01:56 +0000
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-13 10:44 +0000
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-13 11:38 +0000
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-13 14:37 +0000
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-13 15:00 +0000
                Re: better atoi Keith Thompson <kst-u@mib.org> - 2017-02-12 11:15 -0800
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-12 19:25 +0000
                Re: better atoi Keith Thompson <kst-u@mib.org> - 2017-02-12 11:54 -0800
                Re: better atoi supercat@casperkitty.com - 2017-02-12 13:13 -0800
    Re: better atoi Keith Thompson <kst-u@mib.org> - 2017-02-10 15:16 -0800
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 22:01 -0700
        Re: better atoi Keith Thompson <kst-u@mib.org> - 2017-02-11 01:30 -0800
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 22:26 -0700
    Re: better atoi Nick Bowler <nbowler@draconx.ca> - 2017-02-11 00:26 +0000
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 22:32 -0700
    Re: better atoi "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-19 11:10 -0500

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