Re: Non-constant initializers

From	James Kuyper <jameskuyper@verizon.net>
Newsgroups	comp.lang.c
Subject	Re: Non-constant initializers
Date	2011-05-14 16:01 -0400
Organization	A noiseless patient Spider
Message-ID	<iqmn34$4f2$1@dont-email.me> (permalink)
References	(6 earlier) <e68b19561ee2543-31bc7@gmail.com> <iqhrt1$v8n$1@dont-email.me> <9322eedb3a632f5-29a98@gmail.com> <iqmh5c$faj$1@dont-email.me> <351fe53469ed0a6-fdb69@gmail.com>

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On 05/14/2011 03:10 PM, Uncle Steve wrote:
> On Sat, May 14, 2011 at 02:19:25PM -0400, Eric Sosman wrote:
>> On 5/14/2011 1:59 PM, Uncle Steve wrote:
>>> On Thu, May 12, 2011 at 06:53:02PM -0500, Shao Miller wrote:
>>>> On 5/12/2011 6:22 PM, Uncle Steve wrote:
>>>>> [...] I would like to declare:
>>>>>
>>>>> int foops[] = howmuchfoo(void);
>>>>>
>>>>> and have everything work as I expect...
>>>> [...]
>>>>
>>>> - In your code example, is howmuchfoo() supposed to be returning an
>>>> array of 'int' or a single 'int'?
>>>
>>> I don't see how that's relevant to the question.
>>
>>     The point is that the one-line fragment you posted is not
>> valid C, not if `howmuchfoo(void)' is any kind of function at all.
> 
> Yes, and I figured out that I had a misconception of how gcc handles
> non-constant initilizers.  I've already admitted that I'm not coding
> anything specific at the moment, and instead /contemplating/ an
> approach to solving a particular problem, of which variable
> initialization is a part.
> 
>> (If `howmuchfoo' is a function-like macro, it can of course expand
>> at compile-time into pretty much anything.)  But if it's a function
>> call, the fragment is meaningless regardless of what scope it appears
>> in -- which means that by exhibiting it you have conveyed no meaning
>> to anyone.  It is as if you had offered `int foops[] = !<petunia/>;'
>> and expected people to understand you.  If you want to be understood,
>> you'll have to explain yourself more clearly.
> l
> I think that I'm being clear enough here.

You think incorrectly. howmuchfoo() can't be a function call. It could
be a function-like macro, but if so, the possibilities are too
open-ended to be discussed in the abstract; we need information about
the nature of that macro before your question can be addressed.

> ...  The problem may be that
> the subtleties associated with these issues are difficult to
> articulate.  If you don't like my humor, say so.

It has nothing to do with your sense of humor.

...
>>     Something that strikes me as odd is that you(?) started this
>> thread with the statement that you(?) sought a "maximally portable"
>> solution.  Why, then, all this haring off after blatantly non-
>> portable approaches?  Lost sight of the objective, or just trolling?
> 
> I don't see where I've committed to any "blatantly" non-portable
> approaches.  In actual point of fact I've been asking about certain
> compiler features and their actual prevalence in the field.

By definition, compiler features mandated by the standard are available
on every single fully conforming implementation. Therefore, code which
relies on any feature that is less than universally prevalent (such as
zero-length arrays) is non-portable.
-- 
James Kuyper

Thread

Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 22:59 +0000
  Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:07 +1200
    Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:17 +0000
      Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:20 +1200
        Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:30 +0000
          Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:34 +1200
            Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-12 16:52 -0700
              Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 00:13 +0000
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-14 01:28 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 13:52 -0400
                Re: Non-constant initializers kym@kymhorsell.com - 2011-05-14 01:54 +0000
                Re: Non-constant initializers Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-14 01:07 -0700
                Re: Non-constant initializers kym@kymhorsell.com - 2011-05-14 09:22 +0000
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 17:14 +0000
            Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 00:11 +0000
  Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-12 18:08 -0500
    Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-12 19:22 -0400
      Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-12 18:53 -0500
        Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 13:59 -0400
          Re: Non-constant initializers Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-14 14:19 -0400
            Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 15:04 -0500
            Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 15:10 -0400
              Re: Non-constant initializers James Kuyper <jameskuyper@verizon.net> - 2011-05-14 16:01 -0400
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 16:57 -0400
          Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 14:30 -0500
            Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 15:25 -0400
              Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-14 13:05 -0700
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 17:00 -0400
              Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 16:14 -0500
                Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 16:49 -0500
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 18:21 -0400
                Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 21:26 -0500
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-15 14:01 -0400
              Re: Non-constant initializers Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-14 17:45 -0400
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 18:09 -0400
                Re: Non-constant initializers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-15 04:01 +0100
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-15 13:26 -0400
                Re: Non-constant initializers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-16 02:32 +0100
              Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-15 03:59 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 04:49 -0400
                Re: Non-constant initializers pete <pfiland@mindspring.com> - 2011-05-16 07:27 -0400
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 09:24 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-16 19:10 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 21:23 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-16 19:10 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 21:16 -0400
                Re: Non-constant initializers James Kuyper <jameskuyper@verizon.net> - 2011-05-16 21:37 -0400
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 22:42 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-17 02:40 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 22:50 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-17 04:14 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-17 17:37 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-17 22:22 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-17 18:33 -0400
                Re: Non-constant initializers Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-05-18 01:58 -0700
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-18 12:45 -0400
                Re: Non-constant initializers "io_x" <a@b.c.invalid> - 2011-05-18 19:30 +0200
                Re: Non-constant initializers Dr Nick <3-nospam@temporary-address.org.uk> - 2011-05-18 20:01 +0100
                Re: bug-free C code (was: Non-constant initializers) Seebs <usenet-nospam@seebs.net> - 2011-05-19 02:21 +0000
                Re: bug-free C code (was: Non-constant initializers) Keith Thompson <kst-u@mib.org> - 2011-05-18 20:00 -0700
                Re: bug-free C code (was: Non-constant initializers) Seebs <usenet-nospam@seebs.net> - 2011-05-19 03:14 +0000
                Re: bug-free C code (was: Non-constant initializers) Keith Thompson <kst-u@mib.org> - 2011-05-19 07:49 -0700
                Re: bug-free C code (was: Non-constant initializers) Seebs <usenet-nospam@seebs.net> - 2011-05-19 15:16 +0000
                Re: bug-free C code Ben Pfaff <blp@cs.stanford.edu> - 2011-05-18 20:02 -0700
                Re: bug-free C code Keith Thompson <kst-u@mib.org> - 2011-05-18 20:09 -0700
                Re: bug-free C code Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-18 23:24 -0400
                Re: bug-free C code Angel <angel+news@spamcop.net> - 2011-05-19 06:39 +0000
                Re: bug-free C code Keith Thompson <kst-u@mib.org> - 2011-05-19 08:05 -0700
                Re: bug-free C code Angel <angel+news@spamcop.net> - 2011-05-19 16:22 +0000
                Re: bug-free C code Keith Thompson <kst-u@mib.org> - 2011-05-19 11:36 -0700
                Re: bug-free C code Ben Pfaff <blp@cs.stanford.edu> - 2011-05-19 12:21 -0700
                Re: bug-free C code Keith Thompson <kst-u@mib.org> - 2011-05-19 13:12 -0700
                Re: bug-free C code gazelle@shell.xmission.com (Kenny McCormack) - 2011-05-19 21:52 +0000
                Re: bug-free C code Angel <angel+news@spamcop.net> - 2011-05-19 22:16 +0000
                Re: bug-free C code Shao Miller <sha0.miller@gmail.com> - 2011-05-19 17:25 -0500
                Re: bug-free C code Kenneth Brody <kenbrody@spamcop.net> - 2011-05-20 13:32 -0400
                Re: bug-free C code gazelle@shell.xmission.com (Kenny McCormack) - 2011-05-19 21:51 +0000
                Re: bug-free C code Kenneth Brody <kenbrody@spamcop.net> - 2011-05-20 13:30 -0400
                Re: bug-free C code "Joel C. Salomon" <joelcsalomon@gmail.com> - 2011-05-18 23:13 -0400
                Re: bug-free C code Dr Nick <3-nospam@temporary-address.org.uk> - 2011-05-19 08:23 +0100
      Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-13 00:15 +0000
      Re: Non-constant initializers "io_x" <a@b.c.invalid> - 2011-05-13 11:01 +0200
    Re: Non-constant initializers Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-12 16:30 -0700
  Re: Non-constant initializers Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-12 16:15 -0700
    Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:28 +0000
  Re: Non-constant initializers Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-12 18:01 -0600
    Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-12 18:15 -0700
      Re: Non-constant initializers Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-12 22:56 -0600
        Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-13 05:18 +0000
          Re: Non-constant initializers Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-13 09:10 -0600
            Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-13 20:56 +0000
      Re: Non-constant initializers Tim Rentsch <txr@alumni.caltech.edu> - 2011-05-18 23:47 -0700
        Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-19 08:15 -0700
    Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-13 23:57 +0000

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