Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]);

From	BartC <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]);
Date	2017-01-01 14:52 +0000
Organization	A noiseless patient Spider
Message-ID	<o4b511$t2j$1@dont-email.me> (permalink)
References	(9 earlier) <5868defa.4980093@news.xs4all.nl> <o4apes$n3q$1@dont-email.me> <87ful3q9bt.fsf@bsb.me.uk> <o4arsj$uqe$1@dont-email.me> <87a8bbq6ef.fsf@bsb.me.uk>

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On 01/01/2017 13:03, Ben Bacarisse wrote:
> BartC <bc@freeuk.com> writes:

>> All I can find is something
>> that says they can never overflow because the values wrap around.
>
> From which a set of very useful properties follow.

Sure. But probably there are more instances in practice where they are 
not useful.

You don't want a pixel value of +250, or near-white, to suddenly become 
black when you add 6. You don't want to have a size_t type to wrap 
around to a plausible in-bounds value when you add multiply its value.

And you don't really want _Bool values to be anything other than 0 or 1. 
Yet if you negate a _Bool with a value of 1, you're liable to end up 
with 4294967295.

>> My original point was that commutative pointer arithmetic is neither
>> useful nor sensible as it leads to the 2[a] of the subject line.
>
> Yes, I know that was your point.  As far as I'm concerned that topic is
> done with -- you think it's neither useful nor sensible and I disagree.

Until you have to explain it to someone for the umpteenth time.

-- 
Bartc

Thread

How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Veek M <vek.m1234@gmail.com> - 2016-12-30 11:35 +0530
  Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Veek M <vek.m1234@gmail.com> - 2016-12-30 11:39 +0530
    Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Barry Schwarz <schwarzb@dqel.com> - 2016-12-29 22:24 -0800
      Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); raltbos@xs4all.nl (Richard Bos) - 2017-01-01 10:56 +0000
        Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-02 02:40 -0800
          Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); raltbos@xs4all.nl (Richard Bos) - 2017-01-03 21:09 +0000
            Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-13 16:30 -0800
  Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Keith Thompson <kst-u@mib.org> - 2016-12-29 23:35 -0800
  Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); jt@toerring.de (Jens Thoms Toerring) - 2016-12-30 09:59 +0000
    Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2016-12-30 10:43 +0000
      Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-30 12:55 +0000
        Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2016-12-30 13:12 +0000
          Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-30 14:37 +0000
            Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2016-12-30 16:06 +0000
              Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Keith Thompson <kst-u@mib.org> - 2016-12-30 08:41 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2016-12-30 17:31 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-30 19:20 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2016-12-30 19:41 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2016-12-30 12:46 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-31 00:31 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2016-12-30 11:50 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); raltbos@xs4all.nl (Richard Bos) - 2017-01-01 10:54 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-01 11:35 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-01 12:00 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-01 12:16 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-01 13:03 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-01 14:52 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-01 15:42 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-01 16:14 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-01 17:18 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Keith Thompson <kst-u@mib.org> - 2017-01-01 13:09 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-01 19:24 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); bart4858@gmail.com - 2017-01-01 11:24 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-01 20:05 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Keith Thompson <kst-u@mib.org> - 2017-01-01 13:11 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-01 22:25 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-02 02:00 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-01 13:51 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-01 21:59 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-01 14:34 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-02 02:09 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-02 05:44 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-02 15:18 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-02 15:21 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-02 17:07 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-02 09:53 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-02 23:37 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-02 15:07 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ian Collins <ian-news@hotmail.com> - 2017-01-03 12:11 +1300
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-02 15:46 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-03 00:54 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-03 00:33 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-03 11:11 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-03 11:32 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-03 14:05 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-03 14:23 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-03 16:04 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-03 16:09 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-03 17:23 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2017-01-03 09:00 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-03 20:33 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); luser droog <luser.droog@gmail.com> - 2017-01-03 11:40 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2017-01-03 12:23 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); luser droog <luser.droog@gmail.com> - 2017-01-03 12:39 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2017-01-03 13:51 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 22:58 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2017-01-16 10:24 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-31 08:36 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-14 00:53 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ian Collins <ian-news@hotmail.com> - 2017-01-03 13:13 +1300
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Keith Thompson <kst-u@mib.org> - 2017-01-02 15:51 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-03 00:51 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); jt@toerring.de (Jens Thoms Toerring) - 2017-01-02 23:32 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-02 23:46 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-03 01:00 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-03 00:42 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ian Collins <ian-news@hotmail.com> - 2017-01-03 21:47 +1300
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-03 01:31 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-03 10:34 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-03 11:19 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-03 16:19 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Thompson <dave.thompson2@verizon.net> - 2017-01-18 07:51 -0500
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Gareth Owen <gwowen@gmail.com> - 2017-01-18 21:30 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Richard Heathfield <rjh@cpax.org.uk> - 2017-01-18 21:45 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); raltbos@xs4all.nl (Richard Bos) - 2017-01-18 21:55 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Gareth Owen <gwowen@gmail.com> - 2017-01-19 22:25 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-02 00:08 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-02 02:05 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-01 09:45 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-01 19:20 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2017-01-01 15:26 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2017-01-01 23:48 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-02 00:25 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2017-01-01 16:44 +0100
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Philip Lantz <prl@canterey.us> - 2017-01-01 23:54 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Keith Thompson <kst-u@mib.org> - 2017-01-01 13:25 -0800
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-01 22:36 +0000
                Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2017-01-01 15:38 -0800
        Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); BartC <bc@freeuk.com> - 2016-12-30 13:42 +0000
          Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); David Brown <david.brown@hesbynett.no> - 2016-12-30 15:07 +0100
    Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); supercat@casperkitty.com - 2016-12-30 10:21 -0800
  Re: How is he doing: int a[2] = { 1, 2 }; printf("%d\n", 2[a]); Veek M <vek.m1234@gmail.com> - 2016-12-31 07:37 +0530

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