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Groups > comp.lang.c > #127728
| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Future of C |
| Date | 2018-03-12 18:24 -0700 |
| Organization | None to speak of |
| Message-ID | <lnefkobwe7.fsf@kst-u.example.com> (permalink) |
| References | (10 earlier) <d9d91c28-fb38-400b-8b92-ce7ce7d2b9cd@googlegroups.com> <3r7jne-t3h.ln1@gangtai.grep.be> <8e201938-ada4-42d9-8ae6-13b1047306e2@googlegroups.com> <lnina0c1xg.fsf@kst-u.example.com> <JrEpC.185321$mN7.7780@fx16.am4> |
bartc <bc@freeuk.com> writes:
> On 12/03/2018 23:24, Keith Thompson wrote:
>> supercat@casperkitty.com writes:
[...]
>>> How are programmers supposed to judge whether a
>>> VLA declaration of a given size would be reasonable?
>>
>> Take the above paragraph and replace each occurrence of VLA by
>> constant-length array.
>>
>> #define SOME_BIG_NUMBER /*...*/
>>
>> void func1(void) {
>> int fixed_array[SOME_BIG_NUMBER];
>> }
>>
>> void func2(void) {
>> size_t var = SOME_BIG_NUMBER;
>> int vla[var];
>> }
>
> Nevertheless it is useful for both compiler and programmer when an array
> size is known at compile-time.
Nevertheless, it can be useful to be able to define array objects whose
length is not a compile-time constant. Feel free not to use the feature
if you don't like it.
> Your second example is unrealistic, and probably only happens when
> someone thinks that a const int variable can be used as an array length;
> it can, but only by creating a VLA which might have been unintended.
The second example was not intended to be realistic. It was meant to
parallel the first example as closely as possible, to demonstrate that
VLAs don't introduce any fundamental new problems that don't already
exist for fixed arrays.
> (On Windows, a large fixed array requires special stack allocation code.
> With a VLA, it doesn't know what size it is so needs to use the special
> code even if the size turns out to be small.)
Sure, I'd expect some fairly small fixed overhead for a VLA compared to
a fixed array of the same length.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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Re: Future of C Real Troll <real.troll@trolls.com> - 2018-03-08 11:55 -0400
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Re: Future of C jacobnavia <jacob@jacob.remcomp.fr> - 2018-03-12 11:34 +0100
Re: Future of C "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-03-12 13:17 -0700
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-10 18:00 +0100
Re: Future of C Real Troll <Real.Troll@Trolls.com> - 2018-03-10 17:25 -0400
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-11 00:03 +0100
Re: Future of C David Kleinecke <dkleinecke@gmail.com> - 2018-03-10 16:52 -0800
Re: Future of C Robert Wessel <robertwessel2@yahoo.com> - 2018-03-10 23:41 -0600
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-11 16:15 +0100
Re: Future of C David Kleinecke <dkleinecke@gmail.com> - 2018-03-11 14:31 -0700
Re: Future of C Spiros Bousbouras <spibou@gmail.com> - 2018-03-11 21:50 +0000
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Re: Future of C David Kleinecke <dkleinecke@gmail.com> - 2018-03-11 17:48 -0700
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-12 22:25 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-12 16:18 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-12 16:24 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-12 23:55 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-12 17:14 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-12 18:29 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-13 07:58 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:05 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-13 09:38 -0700
Re: Future of C Melzzzzz <Melzzzzz@zzzzz.com> - 2018-03-13 21:51 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-13 15:06 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 12:22 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-12 18:24 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 01:40 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:11 +0100
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:06 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 09:38 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 16:58 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-12 17:01 -0700
Re: Future of C Ian Collins <ian-news@hotmail.com> - 2018-03-13 12:25 +1300
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-13 10:19 +0100
Re: Future of C jameskuyper@verizon.net - 2018-03-13 07:45 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 16:15 +0000
Re: Future of C jameskuyper@verizon.net - 2018-03-13 10:20 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 17:45 +0000
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 11:51 -0700
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-13 21:12 +0100
Re: Future of C Tim Rentsch <txr@alumni.caltech.edu> - 2018-03-17 10:11 -0700
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-18 05:21 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:16 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 18:05 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 21:28 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 13:39 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 21:57 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 14:26 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 12:23 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 21:22 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 13:02 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-14 08:48 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 17:02 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-14 17:09 +0000
Re: Future of C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-03-14 10:18 -0700
Re: Future of C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-03-14 20:04 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 21:46 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 14:03 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 09:22 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-14 14:55 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 09:36 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-15 07:55 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-16 00:19 +0100
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 13:53 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-14 11:37 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 12:12 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-14 13:04 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 13:37 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-14 14:16 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 15:27 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-14 15:50 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 17:09 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-14 20:18 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 10:25 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-15 11:27 -0700
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Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-15 22:03 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 12:54 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-15 14:31 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 15:27 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-15 15:47 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 16:05 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-16 08:19 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-16 10:23 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-16 17:21 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-16 18:37 -0700
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-16 21:25 -0700
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-20 11:46 +0100
Re: Future of C Tim Rentsch <txr@alumni.caltech.edu> - 2018-03-17 10:50 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-19 14:00 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-19 14:48 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-19 15:21 -0700
Re: Future of C "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-03-19 21:47 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 11:12 +0100
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-15 03:28 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 10:57 +0100
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Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 13:35 +0100
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Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 16:14 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-15 09:56 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 10:45 -0700
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 18:15 +0000
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Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 12:38 -0700
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 20:46 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-15 15:14 -0700
Re: Future of C William Ahern <william@25thandClement.com> - 2018-03-15 22:56 -0700
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-16 00:39 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-19 11:35 +0100
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-19 03:46 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 10:35 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-16 00:36 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 10:40 -0700
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Re: Future of C bartc <bc@freeuk.com> - 2018-03-15 14:43 +0000
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Re: Future of C bartc <bc@freeuk.com> - 2018-03-14 17:35 +0000
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[OT] C vs World Trade Center 9/11 "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-11 23:11 +0800
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 17:34 +0000
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-12 19:33 +0100
Re: Future of C Davs <johndemeert0@gmail.com> - 2018-03-11 17:48 -0700
Re: Future of C Manfred <noname@invalid.add> - 2018-03-13 20:54 +0100
Re: Future of C cprime.twitter@gmail.com - 2018-03-13 13:50 -0700
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