Re: Pre And Post Increment Operator Output

From	"BartC" <bc@freeuk.com>
Newsgroups	comp.programming
Subject	Re: Pre And Post Increment Operator Output
Date	2012-06-22 17:49 +0100
Organization	A noiseless patient Spider
Message-ID	<js27pl$h7c$1@dont-email.me> (permalink)
References	(1 earlier) <js03uf$sb3$1@dont-email.me><js092m$pov$1@dont-email.me> <lnipek8bri.fsf@nuthaus.mib.org><js1gf5$l7v$1@dont-email.me> <0.06d3eacd14619c86d384.20120622143458BST.87ehp7o4fx.fsf@bsb.me.uk> <js21jb$963$1@dont-email.me> <7MudnTZhnIs6EnnSnZ2dnUVZ_qCdnZ2d@earthlink.com>

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"Patricia Shanahan" <pats@acm.org> wrote in message
news:7MudnTZhnIs6EnnSnZ2dnUVZ_qCdnZ2d@earthlink.com...
> On 6/22/2012 8:02 AM, BartC wrote:
> ...
>> This is all true. But I still think that if you ask for opinions as to
>> the
>> result of i=(++i)+(++i)+(++i), when i starts at 0, *outside the context
>> of
>> the C language*, then 6 is a strong contender.
>
> In Java, i does have a specified resulting value. The effect will be the
> same as i=3*i+6.

So it ends up with i=6, when i starts at zero. The case for '6' is
improving..

>
> I don't understand what you mean by "outside the context of the C
> language". How can a code snippet have any meaning at all except in the
> context of a programming language?

In C specifically, such an expression has an undefined value (undefined
behaviour actually). You're not allowed, apparently, to ponder what the
actual result will be, nor what the expectation is, nor even what the 
intention of coder was.

But given suitable definitions of "=" (assignment), "+", and "++" (increment
in-place), which are fairly standard anyway, I think you ought to be allowed
to suggest a likely value of i after:

 i=0
 i=(++i) + (++i) + (++i)

without a particular language in mind.

I suggested in comp.lang.c that the result of the above ought to be 6, in 
line with the original poster's expectations, (before going on to explain 
why it might not be in C), for which I was castigated and even called evil.

-- 
Bartc

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Re: Pre And Post Increment Operator Output "BartC" <bc@freeuk.com> - 2012-06-22 16:02 +0100
  Re: Pre And Post Increment Operator Output Patricia Shanahan <pats@acm.org> - 2012-06-22 08:30 -0700
    Re: Pre And Post Increment Operator Output "BartC" <bc@freeuk.com> - 2012-06-22 17:49 +0100
      Re: Pre And Post Increment Operator Output Patricia Shanahan <pats@acm.org> - 2012-06-22 10:36 -0700
        Re: Pre And Post Increment Operator Output "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2012-06-23 09:57 +0100
      Re: Pre And Post Increment Operator Output Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-06-22 20:53 +0100
        Re: Pre And Post Increment Operator Output "BartC" <bc@freeuk.com> - 2012-06-22 21:35 +0100
          Re: Pre And Post Increment Operator Output Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-06-22 23:19 +0100
            Re: Pre And Post Increment Operator Output "BartC" <bc@freeuk.com> - 2012-06-23 01:15 +0100
  Re: Pre And Post Increment Operator Output Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-06-22 17:44 +0100

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