Re: Continue with learning C

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.lang.c
Subject	Re: Continue with learning C
Date	2016-09-18 21:54 +0200
Organization	A noiseless patient Spider
Message-ID	<nrmrdp$gbl$1@dont-email.me> (permalink)
References	(5 earlier) <nrkd4e$f1q$1@dont-email.me> <8b6d5227-f102-4ca9-b964-45b65485c2dc@googlegroups.com> <nrkm32$dj4$1@dont-email.me> <nrm8ss$dki$1@dont-email.me> <nrmcav$p43$1@dont-email.me>

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On 18/09/16 17:37, BartC wrote:
> On 18/09/2016 15:38, David Brown wrote:
>> On 18/09/16 02:11, Richard Heathfield wrote:
>
>> For small enough pieces of software, or for software that is so critical
>> that the cost of bugs is extremely high, the rounding may mean that you
>> end up with zero bugs.  But for complex commodity software, you
>> absolutely expect to ship with bugs.
>
> Didn't the Space Shuttle have multiple backup computers, one of which
> was programmed by a different team to make sure they didn't share the
> same bugs?
>

I believe it is common practice in avionics to have three independent 
computers for the most critical parts.  Each board must have a different 
processor/microcontroller from a different company, and be programmed by 
independent teams using different development tools.  A majority voting 
system is used to determine the signals that are driven out to the 
actuators, with any differences of opinion leading to alarm bells.

>
>> It is not embarrassing - it is
>> fundamental probability and economics.  To use Malcolm's earlier
>> example, the customer in the USA does not want to pay twice as much for
>> his word processor in order to be sure that customers in Israel can mix
>> Hebrew and English without problems.
>
> And wasn't it Knuth who offered $250(?) for each bug readers discovered
> in his algorithms?

Many people and companies, including Knuth, have offered rewards for 
finding and/or squashing bugs.

>
> So we all expect to make mistakes. Except apparently Richard Heathfield
> (unless his point was about knowingly shipping software with errors that
> you don't tell the users about.)
>

Richard said it was embarrassing to sell software with bugs in it.  That 
is true - though it might be inevitable for most software to ship with 
bugs (known or unknown), and might be economically the right decision to 
ship even with known bugs, it is still embarrassing when bugs are found.

Thread

Continue with learning C Alla _ <modelling.data@gmail.com> - 2016-09-15 05:11 -0700
  Re: Continue with learning C "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-09-15 05:29 -0700
  Re: Continue with learning C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-15 15:01 +0100
  Re: Continue with learning C Richard Heathfield <rjh@cpax.org.uk> - 2016-09-15 15:32 +0100
    Re: Continue with learning C Alla _ <modelling.data@gmail.com> - 2016-09-15 08:10 -0700
    Re: Continue with learning C luser droog <luser.droog@gmail.com> - 2016-09-15 12:06 -0700
      Re: Continue with learning C Richard Heathfield <rjh@cpax.org.uk> - 2016-09-15 21:38 +0100
        Re: Continue with learning C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-16 21:02 -0700
          Re: Continue with learning C "Osmium" <r124c4u102@comcast.net> - 2016-09-17 08:03 -0500
          Re: Continue with learning C Richard Heathfield <rjh@cpax.org.uk> - 2016-09-17 22:38 +0100
            Re: Continue with learning C "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-17 18:14 -0400
              Re: Continue with learning C raltbos@xs4all.nl (Richard Bos) - 2016-09-18 10:47 +0000
              Re: Continue with learning C Alla _ <modelling.data@gmail.com> - 2016-09-19 01:25 -0700
                Re: Continue with learning C Ian Collins <ian-news@hotmail.com> - 2016-09-19 20:51 +1200
                Re: Continue with learning C James Kuyper <jameskuyper@verizon.net> - 2016-09-19 09:49 -0400
                Re: Continue with learning C Richard Heathfield <rjh@cpax.org.uk> - 2016-09-19 15:15 +0100
                Re: Continue with learning C Keith Thompson <kst-u@mib.org> - 2016-09-19 11:39 -0700
                Re: Continue with learning C Reinhardt Behm <rbehm@hushmail.com> - 2016-09-20 09:55 +0800
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-20 08:50 +0200
                Re: Continue with learning C Reinhardt Behm <rbehm@hushmail.com> - 2016-09-20 18:04 +0800
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-20 13:25 +0200
                Re: Continue with learning C Reinhardt Behm <rbehm@hushmail.com> - 2016-09-20 20:18 +0800
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-20 15:25 +0200
                Re: Continue with learning C Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-20 08:45 -0400
                Re: Continue with learning C Reinhardt Behm <rbehm@hushmail.com> - 2016-09-20 22:05 +0800
                Re: Continue with learning C Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-20 10:56 -0400
                Re: Continue with learning C Rosario19 <Ros@invalid.invalid> - 2016-09-19 18:55 +0200
                Re: Continue with learning C Anton Shepelev <anton.txt@gmail.com> - 2016-09-25 01:08 +0300
            Re: Continue with learning C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-17 17:08 -0700
              Re: Continue with learning C Richard Heathfield <rjh@cpax.org.uk> - 2016-09-18 01:11 +0100
                Re: Continue with learning C Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-17 21:32 -0400
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-18 16:27 +0200
                Re: Continue with learning C Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-18 16:08 -0400
                Re: Continue with learning C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-18 07:30 -0700
                Re: Continue with learning C Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-18 16:07 -0400
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-18 16:38 +0200
                Re: Continue with learning C BartC <bc@freeuk.com> - 2016-09-18 16:37 +0100
                Re: Continue with learning C Reinhardt Behm <rbehm@hushmail.com> - 2016-09-18 23:54 +0800
                Re: Continue with learning C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-18 16:56 -0700
                Re: Continue with learning C Richard Heathfield <rjh@cpax.org.uk> - 2016-09-18 17:05 +0100
                Re: Continue with learning C "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-18 12:28 -0400
                Re: Continue with learning C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-18 17:00 -0700
                Re: Continue with learning C Alla _ <modelling.data@gmail.com> - 2016-09-19 01:40 -0700
                Re: Continue with learning C "Osmium" <r124c4u102@comcast.net> - 2016-09-19 08:55 -0500
                Re: Continue with learning C "Osmium" <r124c4u102@comcast.net> - 2016-09-18 11:31 -0500
                Re: Continue with learning C Ian Collins <ian-news@hotmail.com> - 2016-09-19 07:25 +1200
                Re: Continue with learning C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-18 20:36 +0100
                Re: Continue with learning C "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-18 15:45 -0400
                Re: Continue with learning C Rosario19 <Ros@invalid.invalid> - 2016-09-19 18:58 +0200
                Re: Continue with learning C "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-09-18 09:55 -0700
                Re: Continue with learning C "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-09-18 10:12 -0700
                Re: Continue with learning C luser droog <luser.droog@gmail.com> - 2016-09-18 13:11 -0700
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-18 21:54 +0200
                Re: Continue with learning C supercat@casperkitty.com - 2016-09-18 15:58 -0700
                Re: Continue with learning C Richard Heathfield <rjh@cpax.org.uk> - 2016-09-19 07:09 +0100
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-19 10:04 +0200
                Re: Continue with learning C BartC <bc@freeuk.com> - 2016-09-19 10:38 +0100
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-19 13:29 +0200
                Re: Continue with learning C supercat@casperkitty.com - 2016-09-19 08:04 -0700
                Re: Continue with learning C Reinhardt Behm <rbehm@hushmail.com> - 2016-09-20 09:33 +0800
                Re: Continue with learning C supercat@casperkitty.com - 2016-09-19 20:47 -0700
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-20 09:00 +0200
                Re: Continue with learning C Reinhardt Behm <rbehm@hushmail.com> - 2016-09-20 17:59 +0800
                Re: Continue with learning C Ike Naar <ike@iceland.freeshell.org> - 2016-09-20 17:24 +0000
                Re: Continue with learning C David Brown <david.brown@hesbynett.no> - 2016-09-20 08:57 +0200
                Re: Continue with learning C supercat@casperkitty.com - 2016-09-20 10:53 -0700
                Re: Continue with learning C Reinhardt Behm <rbehm@hushmail.com> - 2016-09-19 13:19 +0800
                Re: Continue with learning C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-19 01:30 +0100
      Re: Continue with learning C Alla _ <modelling.data@gmail.com> - 2016-09-19 01:15 -0700
  Re: Continue with learning C Barry Schwarz <schwarzb@dqel.com> - 2016-09-15 12:38 -0700
  Re: Continue with learning C fir <profesor.fir@gmail.com> - 2016-09-21 11:42 -0700
    Re: Continue with learning C fir <profesor.fir@gmail.com> - 2016-09-21 12:40 -0700
      Re: Continue with learning C fir <profesor.fir@gmail.com> - 2016-09-21 12:49 -0700
      Re: Continue with learning C fir <profesor.fir@gmail.com> - 2016-09-23 14:47 -0700
        Re: Continue with learning C fir <profesor.fir@gmail.com> - 2016-09-23 14:59 -0700

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