Re: What's new in C?

From	James Kuyper <jameskuyper@verizon.net>
Newsgroups	comp.lang.c
Subject	Re: What's new in C?
Date	2012-12-04 16:19 -0500
Organization	A noiseless patient Spider
Message-ID	<50BE68E5.7090105@verizon.net> (permalink)
References	(7 earlier) <6oednaqUAZ5VKyDNnZ2dnUVZ_qadnZ2d@supernews.com> <lnehj6qkah.fsf@nuthaus.mib.org> <Vs-dnda_D-OXUCDNnZ2dnUVZ_rednZ2d@supernews.com> <0.7b0242de075459b63082.20121204125043GMT.874nk20yn0.fsf@bsb.me.uk> <k9lnp9$i6m$1@speranza.aioe.org>

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On 12/04/2012 03:51 PM, glen herrmannsfeldt wrote:
> Ben Bacarisse <ben.usenet@bsb.me.uk> wrote:
>> Cal Dershowitz <cal@example.invalid> writes:
...
>> The discussion you commented on was about whether 'data' must be
>> allocated on "the stack" and the answer is no -- all that's required by
>> the language is that 'data' be created when the declaration is
>> encountered (executed if you like) and that it is destroyed when f
>> returns.  In fact, even that's not required.  The program must behave as
>> if that's what's happening, but a clever compiler might be able to do
>> something else.
> 
> Isn't it allocated on function entry? So, any values needed for the 
> dimensions must be known at entry.

The C standard makes no such requirement. It doesn't have to be
allocated at function entry. Therefore, the values of the expressions
used to set the dimensions need not be known until the flow of control
through the program has reached the point where the VLA is actually defined.

> (PL/I has BEGIN blocks such that you can allocate inside a procedure,
> but C doesn't have those.)

C has blocks, which )if I understand what you're saying correctly) serve
that same purpose. The body of a function is just a special case of a block.

Thread

What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-11-28 19:41 -0700
  Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-28 19:15 -0800
    Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 02:43 -0700
      Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 07:45 -0500
  Re: What's new in C? Noob <root@127.0.0.1> - 2012-11-29 10:36 +0100
    Re: What's new in C? Weland <weland@sdf.lonestar.org> - 2012-11-29 10:17 +0000
    Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:45 -0700
  Re: What's new in C? Weland <weland@sdf.lonestar.org> - 2012-11-29 09:48 +0000
    Re: What's new in C? David Brown <david@westcontrol.removethisbit.com> - 2012-11-29 13:50 +0100
  Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-29 05:55 -0800
    Re: What's new in C? Les Cargill <lcargill99@comcast.com> - 2012-11-29 12:48 -0600
      Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-30 10:46 +0000
        Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-30 05:31 -0800
          Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-11-30 14:22 +0000
          Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-30 15:04 +0000
            Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 16:41 +0000
              Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-11-30 11:49 -0500
              Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-30 10:12 -0800
              Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-30 11:12 -0800
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 22:26 +0000
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-11-30 22:36 +0000
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 23:27 +0000
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:39 -0700
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-04 00:43 -0800
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 03:14 -0700
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-04 12:50 +0000
                Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-12-04 05:54 -0800
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-04 20:51 +0000
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 16:09 -0500
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-04 16:19 -0500
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-04 21:45 +0000
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-05 01:13 +0000
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-04 20:36 -0500
                Re: What's new in C? Robert Wessel <robertwessel2@yahoo.com> - 2012-12-04 20:26 -0600
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-04 18:48 -0800
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-05 02:57 +0000
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-05 01:42 +0000
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 02:06 -0700
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 07:50 -0500
                Re: What's new in C? JohnF <john@please.see.sig.for.email.com> - 2012-12-06 13:46 +0000
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 09:39 -0500
              Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-11-30 15:52 -0500
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:53 -0700
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 08:16 -0500
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-04 21:18 +0000
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 18:04 -0500
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-05 01:19 +0000
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 21:05 -0500
                Re: What's new in C? Noob <root@127.0.0.1> - 2012-12-05 16:45 +0100
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 01:45 -0700
                Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 08:12 -0500
                Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-06 21:13 +0000
                Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-06 09:15 -0500
                Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-12 18:28 -0700
        Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-30 11:22 -0800
          Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 03:04 -0700
  Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-29 18:19 +0000
    Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-29 11:41 -0800
  Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-11-30 20:50 +0000
    Re: What's new in C? Jens Gustedt <jens.gustedt@loria.fr> - 2012-11-30 23:35 +0100
      Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-05 03:26 +0000
        Re: What's new in C? gwowen <gwowen@gmail.com> - 2012-12-05 23:49 -0800
          Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 01:49 -0700
          Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 07:55 +0000
            Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 13:29 +0000
              Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 15:23 +0000
                Re: What's new in C? Martin Shobe <martin.shobe@yahoo.com> - 2012-12-08 17:46 +0000
                Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-12-08 10:45 -0800
                Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 19:32 +0000
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 18:55 +0000
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 08:26 +1300
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 20:12 +0000
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 09:18 +1300
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 21:21 +0000
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 10:27 +1300
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 13:36 -0800
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 12:59 -0800
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 22:10 +0000
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 16:15 -0800
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 14:23 +1300
                Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 14:20 +1300
                Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 11:32 -0800
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-09 02:52 +0000
                Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-09 02:53 +0000
                Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 20:08 +0000
                Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 20:25 +0000

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