Re: Non-constant initializers

From	Dr Nick <3-nospam@temporary-address.org.uk>
Newsgroups	comp.lang.c
Subject	Re: Non-constant initializers
Date	2011-05-18 20:01 +0100
Message-ID	<87vcx74yuc.fsf@temporary-address.org.uk> (permalink)
References	(7 earlier) <slrnit3srt.2gmi.usenet-nospam@guild.seebs.net> <1e4faf063b586a4-388ce@gmail.com> <slrnit5spp.kqp.usenet-nospam@guild.seebs.net> <8428af69a40e6b6-f9d86@gmail.com> <4dd40205$0$38648$4fafbaef@reader1.news.tin.it>

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"io_x" <a@b.c.invalid> writes:

> "Uncle Steve" <stevet810@gmail.com> ha scritto nel messaggio
> news:8428af69a40e6b6-f9d86@gmail.com...
>> On Tue, May 17, 2011 at 10:22:20PM +0000, Seebs wrote:
>>> On 2011-05-17, Uncle Steve <stevet810@gmail.com> wrote:
>>> > Your approach to the problem assumes bugs a priori.
>>>
>>> Why, yes.
>>>
>>> I am totally open to reconsidering this if I am ever exposed to an example
>>> of a bug-free program.  And no, I haven't seen one yet.  And I'm including
>>> things like "an assembly program which exists only to execute a single
>>> instruction which takes no operands".
>>
>> Obviously, the existence of a bug-free program would be a matter of
>> some significance to the computer science community.  This might be a
>> fruitful research topic for a team of committed graduate students...
>> Surely there would be a paper in it *if* such a thing could be found.
>
> easy
> if a routine can have its input in some range example 1..1000
> it is possible to show that for all valid input it return the right
> answer; for invalid input it return always error

Not necessarily.  And of all the places to make that statement,
comp.lang.c is one of the worst.

Consider a C program that does this but reads or writes one off the end
of an array.  It may well work perfectly on testing, and in production
for months, until one day the machine is particularly busy and it gets a
non-zero'd chunk of memory and suddenly returns the wrong result - or
just crashes.  I've seen this happen (OK, confession time, I caused it).
-- 
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Plan trips, see photos, check facilities  | http://canalplan.org.uk

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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