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Re: Fortran Guy Learning C - Structures...

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: Fortran Guy Learning C - Structures...
Date 2015-02-09 21:54 +0000
Organization A noiseless patient Spider
Message-ID <87lhk692do.fsf@bsb.me.uk> (permalink)
References (9 earlier) <7fc0036a-112b-45e1-94c5-f54536464ef3@googlegroups.com> <7uufdad245u251a7r74ledo8au0alvbqhb@4ax.com> <507b368f-7ae8-410a-b7e6-e42f389fb2e3@googlegroups.com> <8761bb2ht5.fsf@bsb.me.uk> <6bfaa415-d10a-4a1d-a001-ead96b92f11e@googlegroups.com>

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Malcolm McLean <malcolm.mclean5@btinternet.com> writes:

> On Monday, February 9, 2015 at 4:03:43 PM UTC, Ben Bacarisse wrote:
>> 
>> > C doesn't make the array / buffer distinction very well.
>> 
>> Can you give some examples of those that do, or is this a failing shared
>> by most programming languages?
>> 
> C++ has a widely used "vector" type, which most people think of as the C++
> array. They've actually used the term "array" for a more restrictive type.
>
> A vector has a reserve() operation which sets the buffer size, and a
> size() access member which returns the number of actual initialised
> elements.

Well that does help explain your odd use of the terms.  The phrase
"array / buffer distinction" made me think that objects were one or the
other, but it's odder than that.  An MM-array is a portion of an
MM-buffer that is marked as in use in some manner.  Is that about it?

> A fault with C++ is that people often have to use the
> default constructor to create a null element, but technically a vector
> can't contain null, uninitialised, blocked or otherwise invalid
> elements.

[Aside: I thought they could.  std::vector "default constructs" elements
when doing a resize() (or setting the size) and POD types like int have
trivial default constructors that do nothing.  Mind you, I am no C++
expert and there is some evidence that this is a hard matter to pin down
and one that not been left alone in various language revisions.]

<snip>
> Fortran is the opposite. Really it just has buffers. You can of course
> declare an array which is the same size as a buffer, but there's no
> way of generating an array of size determined at runtime, you pass in
> the buffer together with its size to subroutines, together with a
> count variable giving the number of elements actually used.

I can't follow this and it seems at odds with what I know about
Fortran.  Are you discounting allocated arrays?  What about arrays
declared like this:

  subroutine s(n)
   integer, dimension (n) :: array_with_runtime_size
   ...

I'm missing the key thing that makes Fortran an example of making the
array/buffer distinction where C does not, even it makes it by being at
one end of the spectrum.

> However to
> be fair, Fortran programmers also talk loosely about arrays when they
> mean buffers.
>
> The buffer / array distinction is an issue with C because C doesn't
> allow dynamic construction of 2D contiguous arrays.

That's puzzling.  These may be more words in MM speak but using the
usual meanings both

  int n, m;
  ...
  int darray[n][m];

and

  int (*dp)[m] = malloc(n * sizeof **dp);

dynamically construct contiguous 2D arrays.

> So often it's
> necessary to pass in base pointer, width and height. However what you
> have is a 2D array.  Alternatively, you can create an array of pointers
> and allocate each row separately. So now we've also got a 2D array, but
> the buffer structure is different.

I don't think your use of the terms is helping to make matters clear.

-- 
Ben.

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Thread

Fortran Guy Learning C - Structures... jeffkrob16@gmail.com - 2015-02-03 09:33 -0800
  Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-03 17:59 +0000
  Re: Fortran Guy Learning C - Structures... James Kuyper <jameskuyper@verizon.net> - 2015-02-03 13:01 -0500
  Re: Fortran Guy Learning C - Structures... Barry Schwarz <schwarzb@dqel.com> - 2015-02-03 10:49 -0800
  Re: Fortran Guy Learning C - Structures... Richard Heathfield <invalid@see.sig.invalid> - 2015-02-03 18:54 +0000
  Fortran Guy Learning C - Structures... asetofsymbols@gmail.com - 2015-02-03 11:50 -0800
    Fortran Guy Learning C - Structures... asetofsymbols@gmail.com - 2015-02-03 12:07 -0800
    Re: Fortran Guy Learning C - Structures... Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-02-03 15:14 -0500
    Re: Fortran Guy Learning C - Structures... Barry Schwarz <schwarzb@dqel.com> - 2015-02-03 15:06 -0800
      Re: Fortran Guy Learning C - Structures... asetofsymbols@gmail.com - 2015-02-03 22:19 -0800
  Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-03 21:40 +0000
    Re: Fortran Guy Learning C - Structures... asetofsymbols@gmail.com - 2015-02-03 22:56 -0800
      Re: Fortran Guy Learning C - Structures... asetofsymbols@gmail.com - 2015-02-03 23:02 -0800
      Re: Fortran Guy Learning C - Structures... asetofsymbols@gmail.com - 2015-02-04 00:01 -0800
  Re: Fortran Guy Learning C - Structures... jeffkrob16@gmail.com - 2015-02-04 10:53 -0800
    Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-04 11:21 -0800
    Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-04 19:32 +0000
    Re: Fortran Guy Learning C - Structures... Barry Schwarz <schwarzb@dqel.com> - 2015-02-04 11:59 -0800
    Re: Fortran Guy Learning C - Structures... hormelfree@gmail.com - 2015-02-04 15:30 -0800
      Re: Fortran Guy Learning C - Structures... jeffkrob16@gmail.com - 2015-02-04 19:41 -0800
        Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-05 04:06 +0000
          Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-05 10:36 +0000
            Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-05 10:59 +0000
            Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-05 11:03 +0000
            Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-05 12:30 +0000
              Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-05 12:46 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-05 12:49 +0000
            Re: Fortran Guy Learning C - Structures... hormelfree@gmail.com - 2015-02-05 15:08 -0800
          Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-05 08:48 -0800
          Re: Fortran Guy Learning C - Structures... hormelfree@gmail.com - 2015-02-05 15:16 -0800
            Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-05 23:35 +0000
              Re: Fortran Guy Learning C - Structures... hormelfree@gmail.com - 2015-02-07 12:11 -0800
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-07 12:22 -0800
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-07 22:03 +0000
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-07 14:47 -0800
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-07 17:15 -0800
                Re: Fortran Guy Learning C - Structures... Ian Collins <ian-news@hotmail.com> - 2015-02-08 17:22 +1300
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-08 02:47 -0800
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-08 11:20 -0800
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-08 14:36 -0800
                Re: Fortran Guy Learning C - Structures... Ian Collins <ian-news@hotmail.com> - 2015-02-09 11:51 +1300
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-08 15:02 -0800
                Re: Fortran Guy Learning C - Structures... Geoff <geoff@invalid.invalid> - 2015-02-08 16:55 -0800
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-09 03:24 -0800
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-09 11:56 +0000
                Re: Fortran Guy Learning C - Structures... David Brown <david.brown@hesbynett.no> - 2015-02-09 14:25 +0100
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-09 14:00 +0000
                Re: Fortran Guy Learning C - Structures... David Brown <david.brown@hesbynett.no> - 2015-02-09 15:26 +0100
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-09 14:39 +0000
                Re: Fortran Guy Learning C - Structures... David Brown <david.brown@hesbynett.no> - 2015-02-09 16:59 +0100
                Re: Fortran Guy Learning C - Structures... raltbos@xs4all.nl (Richard Bos) - 2015-02-09 16:01 +0000
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-09 13:39 +0000
                Re: Fortran Guy Learning C - Structures... James Kuyper <jameskuyper@verizon.net> - 2015-02-09 09:46 -0500
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-09 14:50 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-09 08:22 -0800
                Re: Fortran Guy Learning C - Structures... gazelle@shell.xmission.com (Kenny McCormack) - 2015-02-09 13:24 +0000
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-09 16:03 +0000
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-09 11:01 -0800
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-09 21:54 +0000
                Re: Fortran Guy Learning C - Structures... Öö Tiib <ootiib@hot.ee> - 2015-02-09 19:22 -0800
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-10 11:34 +0000
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-10 14:15 +0000
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-10 00:38 -0800
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-10 09:21 +0000
                Re: Fortran Guy Learning C - Structures... Ian Collins <ian-news@hotmail.com> - 2015-02-10 22:24 +1300
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-10 09:25 +0000
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-10 09:03 -0800
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-10 17:12 +0000
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-10 09:56 -0800
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-10 18:12 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-10 11:24 -0800
                Re: Fortran Guy Learning C - Structures... gazelle@shell.xmission.com (Kenny McCormack) - 2015-02-10 20:18 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-10 09:16 -0800
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-10 22:12 +0000
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-11 02:58 +0000
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-10 19:00 -0800
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-11 07:56 +0000
                Re: Fortran Guy Learning C - Structures... David Thompson <dave.thompson2@verizon.net> - 2015-02-22 18:08 -0500
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-10 16:01 -0800
                Re: Fortran Guy Learning C - Structures... Ian Collins <ian-news@hotmail.com> - 2015-02-10 11:26 +1300
                Re: Fortran Guy Learning C - Structures... David Brown <david.brown@hesbynett.no> - 2015-02-10 10:29 +0100
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-09 08:32 -0800
                Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-09 11:09 -0800
                Re: Fortran Guy Learning C - Structures... gazelle@shell.xmission.com (Kenny McCormack) - 2015-02-09 19:39 +0000
                Re: Fortran Guy Learning C - Structures... Martin Shobe <martin.shobe@yahoo.com> - 2015-02-09 14:04 -0600
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-09 12:24 -0800
                Re: Fortran Guy Learning C - Structures... David Brown <david.brown@hesbynett.no> - 2015-02-10 10:34 +0100
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-08 11:42 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-07 22:50 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-07 17:07 -0800
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-08 11:29 +0000
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-08 12:14 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-08 13:44 +0000
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-08 22:39 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-08 11:12 -0800
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-08 20:01 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-08 20:06 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-08 21:04 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-08 21:11 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-08 23:48 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-08 13:30 -0800
                Re: Fortran Guy Learning C - Structures... Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-02-08 16:47 -0500
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-08 14:53 -0800
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-09 02:31 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-09 10:35 +0000
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-09 13:57 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-09 07:59 -0800
                Re: Fortran Guy Learning C - Structures... Öö Tiib <ootiib@hot.ee> - 2015-02-09 18:15 -0800
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-10 05:54 +0000
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-09 16:17 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-08 22:04 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-08 14:57 -0800
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-08 23:45 +0000
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-09 02:53 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-09 09:29 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-09 10:10 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-09 11:24 +0000
                Re: Fortran Guy Learning C - Structures... Ike Naar <ike@iceland.freeshell.org> - 2015-02-09 17:36 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-09 17:56 +0000
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-09 10:51 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-09 11:10 +0000
                Re: Fortran Guy Learning C - Structures... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-02-09 11:25 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-09 11:43 +0000
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-10 02:13 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-10 03:26 +0000
                Re: Fortran Guy Learning C - Structures... raltbos@xs4all.nl (Richard Bos) - 2015-02-09 21:18 +0000
                Re: Fortran Guy Learning C - Structures... Bartc <bc@freeuk.com> - 2015-02-09 23:11 +0000
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-08 12:10 +0000
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-08 11:18 -0800
                Re: Fortran Guy Learning C - Structures... Richard Heathfield <rjh@cpax.org.uk> - 2015-02-08 19:27 +0000
                Re: Fortran Guy Learning C - Structures... hormelfree@gmail.com - 2015-02-09 15:00 -0800
                Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-09 16:00 -0800
        Re: Fortran Guy Learning C - Structures... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-02-05 02:49 -0800
          Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-05 11:16 +0000
          Re: Fortran Guy Learning C - Structures... Keith Thompson <kst-u@mib.org> - 2015-02-05 09:00 -0800
            Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-06 00:29 +0000
              Re: Fortran Guy Learning C - Structures... Robert Wessel <robertwessel2@yahoo.com> - 2015-02-05 19:20 -0600
              Re: Fortran Guy Learning C - Structures... "Charles Richmond" <numerist@aquaporin4.com> - 2015-02-06 16:15 -0600
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-07 00:57 +0000
              Re: Fortran Guy Learning C - Structures... Kaz Kylheku <kaz@kylheku.com> - 2015-02-07 01:40 +0000
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-07 08:22 +0000
                Re: Fortran Guy Learning C - Structures... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-02-07 12:06 +0000
            Re: Fortran Guy Learning C - Structures... John Bode <jfbode1029@gmail.com> - 2015-02-06 15:03 -0800
        Re: Fortran Guy Learning C - Structures... hormelfree@gmail.com - 2015-02-05 15:12 -0800

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