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Groups > comp.lang.c > #27431

Re: callback function

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: callback function
Date 2012-10-20 15:51 -0700
Organization None to speak of
Message-ID <lnd30chi4c.fsf@nuthaus.mib.org> (permalink)
References (1 earlier) <1o8u781nrpll3im14bf0019tg1523qv226@4ax.com> <k5sl4u$re$1@speranza.aioe.org> <6f84885kvafnr4vmb12o1a4o0tgl9u628p@4ax.com> <k5usd7$s6r$1@speranza.aioe.org> <aegn3qFnpi3U17@mid.individual.net>

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Ian Collins <ian-news@hotmail.com> writes:
> On 10/21/12 08:01, Bill Cunningham wrote:
>> Barry Schwarz wrote:
>>
>>> Do you really think the standard should be changed because your
>>> limited understanding of the language does not provide you an obvious
>>> use of the qualifier?
>>
>>      No not if its that useful. It's because of my limited
>> understanding of C that I make this statement. Can you give me a good
>> example of when const is good to use. I've never needed it?
>
> Those of us from an embedded background probably use const more than 
> others.  If something is declared cont, the compiler can place it in 
> read only memory which is typically more plentiful in embedded systems. 
>   So given
>
> const int stuff[] = { 1,2,3,4,5,6,7};
>
> stuff will end up in ROM.  Any attempt to modify it will either fail or 
> cause a crash.  So stuff can only be safely passed to a function with a 
> const qualified parameter.

That's true in that case, but not in all cases.  For example, this:

    const int r = rand();

is perfectly legal, but r can't be placed in ROM.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
    Will write code for food.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-17 17:16 -0400
  Re: callback function John Gordon <gordon@panix.com> - 2012-10-17 21:36 +0000
    Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-17 17:44 -0400
      Re: callback function John Gordon <gordon@panix.com> - 2012-10-17 21:51 +0000
        Re: callback function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-10-18 00:11 +0100
        Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 18:37 -0400
          Re: callback function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-10-19 01:16 +0100
          Re: callback function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-10-20 06:48 -0700
    Re: callback function Ian Collins <ian-news@hotmail.com> - 2012-10-18 10:45 +1300
      Re: callback function pete <pfiland@mindspring.com> - 2012-10-19 14:49 -0400
        Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 16:59 -0400
        Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 17:04 -0400
          Re: callback function Barry Schwarz <schwarzb@dqel.com> - 2012-10-19 14:14 -0700
            Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 17:31 -0400
              Re: callback function Keith Thompson <kst-u@mib.org> - 2012-10-19 14:54 -0700
                Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 18:42 -0400
    Re: callback function James Kuyper <jameskuyper@verizon.net> - 2012-10-17 17:47 -0400
    Re: callback function tom st denis <tom@iahu.ca> - 2012-10-19 04:44 -0700
      Re: callback function James Kuyper <jameskuyper@verizon.net> - 2012-10-19 08:24 -0400
  Re: callback function Barry Schwarz <schwarzb@dqel.com> - 2012-10-17 14:39 -0700
    Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-17 17:50 -0400
      Re: callback function Ian Collins <ian-news@hotmail.com> - 2012-10-18 11:00 +1300
        Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 18:20 -0400
        Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 18:24 -0400
          Re: callback function Barry Schwarz <schwarzb@dqel.com> - 2012-10-18 22:30 -0700
          Re: callback function Ian Collins <ian-news@hotmail.com> - 2012-10-20 11:58 +1300
            Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 19:27 -0400
              Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 19:43 -0400
                Re: callback function Barry Schwarz <schwarzb@dqel.com> - 2012-10-19 21:09 -0700
          Re: callback function Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-10-20 06:53 -0700
      Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-17 19:25 -0400
        Re: callback function Ian Collins <ian-news@hotmail.com> - 2012-10-18 13:34 +1300
          Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-17 20:41 -0400
            Re: callback function Ian Collins <ian-news@hotmail.com> - 2012-10-18 14:37 +1300
              Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 18:17 -0400
                Re: callback function Ian Collins <ian-news@hotmail.com> - 2012-10-20 11:54 +1300
              Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 18:54 -0400
                Re: callback function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-10-19 01:23 +0100
                Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 20:32 -0400
                Re: callback function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-10-19 02:43 +0100
                Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 16:56 -0400
                Re: callback function Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-10-19 22:10 +0100
                Re: callback function Barry Schwarz <schwarzb@dqel.com> - 2012-10-18 22:30 -0700
                Re: callback function Kenneth Brody <kenbrody@spamcop.net> - 2012-10-19 12:37 -0400
                Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 16:52 -0400
    Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-19 18:44 -0400
      Re: callback function Barry Schwarz <schwarzb@dqel.com> - 2012-10-19 21:09 -0700
        Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-20 15:01 -0400
          Re: callback function Keith Thompson <kst-u@mib.org> - 2012-10-20 12:47 -0700
          Re: callback function Les Cargill <lcargill99@comcast.com> - 2012-10-20 14:51 -0500
          Re: callback function Barry Schwarz <schwarzb@dqel.com> - 2012-10-20 14:39 -0700
            Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-20 19:06 -0400
              Re: callback function Barry Schwarz <schwarzb@dqel.com> - 2012-10-20 22:22 -0700
                Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-21 14:35 -0400
                Re: callback function Kenneth Brody <kenbrody@spamcop.net> - 2012-10-22 10:58 -0400
              Re: callback function Bill Cunningham <billcun@suddenlink.net> - 2012-10-24 17:28 -0700
          Re: callback function Ian Collins <ian-news@hotmail.com> - 2012-10-21 11:32 +1300
            Re: callback function Keith Thompson <kst-u@mib.org> - 2012-10-20 15:51 -0700
      Re: callback function Robert Miles <milesrf@Usenet-News.net> - 2012-11-25 22:39 -0600
  Re: callback function Keith Thompson <kst-u@mib.org> - 2012-10-17 17:51 -0700
    Re: callback function Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-10-18 20:34 +0300
    Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 18:15 -0400
      Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 18:27 -0400
      Re: callback function Keith Thompson <kst-u@mib.org> - 2012-10-18 15:47 -0700
        Re: callback function "Bill Cunningham" <billcun@suddenlink.net> - 2012-10-18 18:52 -0400
      Re: callback function blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2012-10-25 10:01 +0000
        Re: callback function Kenneth Brody <kenbrody@spamcop.net> - 2012-10-25 12:44 -0400
          Re: callback function blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2012-10-26 12:48 +0000
  Re: callback function Robert Miles <milesrf@Usenet-News.net> - 2012-11-25 22:13 -0600
    Re: callback function Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-26 03:42 -0800
    Re: callback function James Kuyper <jameskuyper@verizon.net> - 2012-11-26 06:59 -0500
    Re: callback function Keith Thompson <kst-u@mib.org> - 2012-11-26 23:03 -0800

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