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Re: rms from rosettacode

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jt@toerring.de (Jens Thoms Toerring) writes:
> superpollo <superpollo@tznvy.pbz> wrote:
>> so, to summarize: it is not possible for a function that gets an array 
>> passed to figure by herself the size, right?
>
> Correct. And that's because you can't pass an array to a function,
> that's simply not possible in C. All you can pass to a function is
> a pointer to an element (typically the first) of an array (when you
> call a function with an array as an argument the array is silently
> converted to such a pointer to its first element). And with just
> knowing the address of the first element of the array the function
> can't determine the length of the array, thus you have to pass it
> separately. Or, as it already has been pointed out, you could use
> a sentinel element to mark the end of the array - but that re-
> quires that a value existst that never can be a valid data value
> of your array.
>
> The only real way around that would be to wrap the array into
> a structure - structures (in contrast to arrays) can be passed
> to functions. But, of course, there's a downside: when you pass
> around a structure a complete copy of the structure must be cre-
> ated which can be rather time- and memory-consuming.

And the number of elements in the array must be fixed at compile time.
(I suppose you could use a flexible array member, the C99 replacement
for the "struct hack", but you still have to have another mechanism to
get the length.)

-- 
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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rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-27 11:25 +0100
  Re: rms from rosettacode James Kuyper <jameskuyper@verizon.net> - 2011-12-27 06:48 -0500
    Re: rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-27 13:01 +0100
      Re: rms from rosettacode James Kuyper <jameskuyper@verizon.net> - 2011-12-27 07:10 -0500
        Re: rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-27 13:36 +0100
          Re: rms from rosettacode James Kuyper <jameskuyper@verizon.net> - 2011-12-27 10:04 -0500
    Re: rms from rosettacode Keith Thompson <kst-u@mib.org> - 2011-12-27 14:42 -0800
      Re: rms from rosettacode James Kuyper <jameskuyper@verizon.net> - 2011-12-27 18:46 -0500
  Re: rms from rosettacode 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-27 09:49 -0800
  Re: rms from rosettacode "BartC" <bc@freeuk.com> - 2011-12-27 18:14 +0000
    Re: rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-27 19:33 +0100
      Re: rms from rosettacode jt@toerring.de (Jens Thoms Toerring) - 2011-12-27 19:04 +0000
        Re: rms from rosettacode Keith Thompson <kst-u@mib.org> - 2011-12-27 14:45 -0800
        Re: rms from rosettacode blp@cs.stanford.edu (Ben Pfaff) - 2011-12-27 14:57 -0800
      Re: rms from rosettacode "BartC" <bc@freeuk.com> - 2011-12-27 19:06 +0000
        Re: rms from rosettacode Bull in a China Blue Shop <chine.bleu@yahoo.com> - 2011-12-27 16:16 -0800
      Re: rms from rosettacode James Kuyper <jameskuyper@verizon.net> - 2011-12-27 14:11 -0500
      Re: rms from rosettacode Seebs <usenet-nospam@seebs.net> - 2011-12-27 20:13 +0000
      Re: rms from rosettacode Johann Klammer <klammerr@NOSPAM.aon.at> - 2011-12-28 00:23 +0100
      Re: rms from rosettacode 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-27 15:54 -0800
        Re: rms from rosettacode Keith Thompson <kst-u@mib.org> - 2011-12-27 22:53 -0800
          Re: rms from rosettacode Seebs <usenet-nospam@seebs.net> - 2011-12-28 06:29 +0000
          Re: rms from rosettacode 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-28 02:45 -0800
  Re: rms from rosettacode Kaz Kylheku <kaz@kylheku.com> - 2011-12-27 19:53 +0000
    Re: rms from rosettacode Seebs <usenet-nospam@seebs.net> - 2011-12-27 20:13 +0000
    Re: rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-27 21:31 +0100
      Re: rms from rosettacode Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-12-27 20:49 -0500
        Re: rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-28 11:42 +0100
          Re: rms from rosettacode Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-12-29 08:18 -0800
        Re: rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-28 11:54 +0100
          Re: rms from rosettacode Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-12-29 04:12 +0200
            Re: rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-29 14:38 +0100
        Re: rms from rosettacode Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-12-28 02:26 -0800
          Re: rms from rosettacode Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-12-28 21:35 -0500
            Re: rms from rosettacode superpollo <superpollo@tznvy.pbz> - 2011-12-29 14:10 +0100
        Re: rms from rosettacode James Kuyper <jameskuyper@verizon.net> - 2011-12-28 08:03 -0500
          Re: rms from rosettacode "BartC" <bc@freeuk.com> - 2011-12-28 13:32 +0000
            Re: rms from rosettacode Dr Nick <3-nospam@temporary-address.org.uk> - 2011-12-28 13:41 +0000
            Re: rms from rosettacode Kaz Kylheku <kaz@kylheku.com> - 2011-12-28 19:29 +0000
            Re: rms from rosettacode Keith Thompson <kst-u@mib.org> - 2011-12-28 13:47 -0800
            Re: rms from rosettacode Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-12-29 04:19 +0200
      Re: rms from rosettacode Kaz Kylheku <kaz@kylheku.com> - 2011-12-28 19:11 +0000

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