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Re: a doubt about c

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On 06/12/11 11:53 AM, DSF wrote:
> On Sun, 12 Jun 2011 08:58:36 +1200, Ian Collins<ian-news@hotmail.com>
> wrote:
>
>> On 06/12/11 08:41 AM, Angel wrote:
>>> On 2011-06-11, Keith Thompson<kst-u@mib.org>   wrote:
>>>
>>>> What I'd really like to see is for C to adopt C++'s feature, where
>>>> a const object of numeric type whose initializer is a constant
>>>> expression can be used as a constant:
>>>>
>>>>       const int max = 1000;
>>>>       const double pi = 3.14159265358979;
>>>>
>>>> But it's probably too late to add that to C201X.
>>>
>>> Yeah, #defines and macros have their place, but this seems like a much
>>> more natural way to define a numerical constant to me.
>>
>> The place for #define constants is the dustbin of history!
>
>    May I ask why you feel that way?

They are an anachronism.  I don't believe in mixing the preprocessor 
realm (conditional compilation) with the C code realm.  Unfortunately C 
has never adopted the C++ definition of const as compile time constant, 
so we will be stuck with them for a while longer.  I really don't 
understand why this change has never been made.

> #define constants certainly have a
> potential performance benefit over a const variable.  The use of a
> #define constant is often replaced with an immediate value, whereas a
> const variable is likely to be stored in a static memory pool which is
> often part of the program itself.  This leaves the potential for
> slower execution and a larger program size.

Not with a half decent modern compiler.

-- 
Ian Collins

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a doubt about c Ya Shou <zxyzxy12321@gmail.com> - 2011-06-11 06:11 -0700
  Re: a doubt about c James Kuyper <jameskuyper@verizon.net> - 2011-06-11 09:36 -0400
  Re: a doubt about c Angel <angel+news@spamcop.net> - 2011-06-11 14:37 +0000
    Re: a doubt about c Keith Thompson <kst-u@mib.org> - 2011-06-11 11:55 -0700
      Re: a doubt about c Angel <angel+news@spamcop.net> - 2011-06-11 20:41 +0000
        Re: a doubt about c Ian Collins <ian-news@hotmail.com> - 2011-06-12 08:58 +1200
          Re: a doubt about c Shao Miller <sha0.miller@gmail.com> - 2011-06-11 17:09 -0500
          Re: a doubt about c Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-11 18:25 -0400
            Re: a doubt about c Ian Collins <ian-news@hotmail.com> - 2011-06-12 11:43 +1200
            Re: a doubt about c Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-06-12 05:38 -0700
              Re: a doubt about c Roberto Waltman <usenet@rwaltman.com> - 2011-06-12 10:12 -0400
                Re: a doubt about c Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-12 10:59 -0400
                Re: a doubt about c Nobody <nobody@nowhere.com> - 2011-06-15 17:07 +0100
                Re: a doubt about c Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-06-12 11:33 -0700
                Re: a doubt about c James Kuyper <jameskuyper@verizon.net> - 2011-06-15 09:53 -0400
                Re: a doubt about c Dr Nick <3-nospam@temporary-address.org.uk> - 2011-06-16 18:46 +0100
          Re: a doubt about c DSF <notavalid@address.here> - 2011-06-11 18:53 -0500
            Re: a doubt about c Keith Thompson <kst-u@mib.org> - 2011-06-11 16:18 -0700
              Re: a doubt about c Stephen Sprunk <stephen@sprunk.org> - 2011-06-11 21:13 -0500
                Re: a doubt about c Ian Collins <ian-news@hotmail.com> - 2011-06-12 14:56 +1200
                Re: a doubt about c Keith Thompson <kst-u@mib.org> - 2011-06-11 20:24 -0700
                Re: a doubt about c Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-12 08:10 -0400
            Re: a doubt about c Ian Collins <ian-news@hotmail.com> - 2011-06-12 11:49 +1200
        Re: a doubt about c Keith Thompson <kst-u@mib.org> - 2011-06-11 15:36 -0700
      Re: a doubt about c Nobody <nobody@nowhere.com> - 2011-06-12 00:23 +0100
        Re: a doubt about c Seebs <usenet-nospam@seebs.net> - 2011-06-13 14:39 +0000
          Re: a doubt about c Squeamizh <squeamz@hotmail.com> - 2011-06-15 15:44 -0700
            Re: a doubt about c Geoff <geoff@invalid.invalid> - 2011-06-15 19:57 -0700
              Re: a doubt about c "J. J. Farrell" <jjf@bcs.org.uk> - 2011-06-16 18:39 +0100
                Re: a doubt about c Nobody <nobody@nowhere.com> - 2011-06-17 15:39 +0100
                Re: a doubt about c Willem <willem@toad.stack.nl> - 2011-06-17 14:49 +0000
                Re: a doubt about c Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-17 09:14 -0600
                Re: a doubt about c Shao Miller <sha0.miller@gmail.com> - 2011-06-17 12:00 -0500
                Re: a doubt about c Shao Miller <sha0.miller@gmail.com> - 2011-06-17 11:08 -0500
                Re: [OT] Doubt vs. question. (Re: a doubt about c) Shao Miller <sha0.miller@gmail.com> - 2011-06-17 13:00 -0500
                Re: [OT] Doubt vs. question. (Re: a doubt about c) Shao Miller <sha0.miller@gmail.com> - 2011-06-22 19:01 -0500
                Re: a doubt about c Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-17 09:14 -0600
                Re: a doubt about c Seebs <usenet-nospam@seebs.net> - 2011-06-17 22:16 +0000
                Re: a doubt about c "J. J. Farrell" <jjf@bcs.org.uk> - 2011-06-18 02:24 +0100
      Re: a doubt about c Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-11 23:09 -0600
      [OT] Doubt vs. question.  (Re: a doubt about c) Roberto Waltman <usenet@rwaltman.com> - 2011-06-12 10:05 -0400
        Re: [OT] Doubt vs. question.  (Re: a doubt about c) Keith Thompson <kst-u@mib.org> - 2011-06-12 11:22 -0700
          Re: [OT] Doubt vs. question.  (Re: a doubt about c) Ben Pfaff <blp@cs.stanford.edu> - 2011-06-12 11:44 -0700
        Re: [OT] Doubt vs. question.  (Re: a doubt about c) Ralph Spitzner <rasp@spitzner.org> - 2011-06-13 11:31 +0200
          Re: [OT] Doubt vs. question.  (Re: a doubt about c) James Kuyper <jameskuyper@verizon.net> - 2011-06-15 10:03 -0400
            Re: [OT] Doubt vs. question. (Re: a doubt about c) Dr Nick <3-nospam@temporary-address.org.uk> - 2011-06-17 07:52 +0100
            Re: [OT] Doubt vs. question.  (Re: a doubt about c) Michael Press <rubrum@pacbell.net> - 2011-06-19 00:41 -0700
              Re: [OT] Doubt vs. question.  (Re: a doubt about c) James Kuyper <jameskuyper@verizon.net> - 2011-06-19 07:04 -0400
                Re: [OT] Doubt vs. question.  (Re: a doubt about c) Bill Waddington <william.waddington@beezmo.com> - 2011-06-23 11:03 -0700
  Re: a doubt about c Shao Miller <sha0.miller@gmail.com> - 2011-06-11 11:23 -0500
    Re: a doubt about c pete <pfiland@mindspring.com> - 2011-06-11 13:56 -0400
      Re: a doubt about c "dr.oktopus" <blindwilly@freeonline.zzn.com> - 2011-06-11 12:53 -0700
        Re: a doubt about c Lew Pitcher <lpitcher@teksavvy.com> - 2011-06-11 16:01 -0400
        Re: a doubt about c Keith Thompson <kst-u@mib.org> - 2011-06-11 13:07 -0700
        Re: a doubt about c Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-11 14:13 -0600
          Re: a doubt about c Nobody <nobody@nowhere.com> - 2011-06-11 23:31 +0100
            Re: a doubt about c pete <pfiland@mindspring.com> - 2011-06-11 20:07 -0400
            Re: a doubt about c Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-06-11 23:05 -0600
      Re: a doubt about c Shao Miller <sha0.miller@gmail.com> - 2011-06-11 16:42 -0500
        Re: a doubt about c "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2011-06-11 14:23 -0700
          Re: a doubt about c Shao Miller <sha0.miller@gmail.com> - 2011-06-11 17:27 -0500
            Re: a doubt about c Keith Thompson <kst-u@mib.org> - 2011-06-11 15:42 -0700
  Re: a doubt about c Seebs <usenet-nospam@seebs.net> - 2011-06-13 14:39 +0000

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