Groups > comp.lang.java.programmer > #26504

Re: Possible loss of precision

Path	csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!news.albasani.net!.POSTED!not-for-mail
From	Michael Jung <miju@golem.phantasia.org>
Newsgroups	comp.lang.java.programmer
Subject	Re: Possible loss of precision
Date	Thu, 14 Nov 2013 20:39:42 +0100
Organization	albasani.net
Lines	20
Message-ID	<87txfe22o1.fsf@golem.phantasia.org> (permalink)
References	<loss-20131113231933@ram.dialup.fu-berlin.de>
Mime-Version	1.0
Content-Type	text/plain; charset=iso-8859-1
Content-Transfer-Encoding	8bit
X-Trace	news.albasani.net c1UcvKIZA7ocmc6uOfo/QD+VoikDPl2gb+2byyoXXJ59paRR86RyzbMzqo4pHdAr6gyWmpXFXYldundKZf71Y+Kpa5Myenvz2nvpjXYPsU7llWP0MeHy7woRBbJJenJ8
NNTP-Posting-Date	Thu, 14 Nov 2013 19:39:43 +0000 (UTC)
Injection-Info	news.albasani.net; logging-data="9PIzizP/GbiSiG0sGk9zdpZtJ6283mBrFUi9f3YF+Bw3sa8YIFZ9plHbPI/VvruwQnlaZII9h4YlaW9OtgvJ60dQ7Xvpt6tFFbjMqQbOfeCZxTZVmAPzbJo9e0BG69Ct"; mail-complaints-to="abuse@albasani.net"
User-Agent	Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux)
Cancel-Lock	sha1:qvCG+USz2jPbpNwdDUIAZq+bnw8= sha1:YGSulu4qRnagDp2bFPBRC83w/rc=
Xref	csiph.com comp.lang.java.programmer:26504

Show key headers only | View raw

ram@zedat.fu-berlin.de (Stefan Ram) writes:
> char x = 'C' + 1;
> x = x + 1;
>   in a block, one gets an error message
> »possible loss of precision«
>   for »x = x + 1«. Ok, fair enough: »x + 1« has type »int«,
>   and precision is lost when assigning this to the variable x
>   of type char.
>   I was somewhat surprised, though, that »char x = 'C' + 1;«
>   does not yield an error, even though the type of »'C' + 1«
>   is int, too. Possibly, this time, the compiler can figure
>   out that the actual value still fits into a char.
>   But then, »int i = 2.0;« gives an error, even though the
>   compiler should see that »2.0« can be represented as an int.

You are right that x+1 is "promoted" to int and the second assignment
fails.  In the other cases the compiler will follow JLS 15.28 => 5.2.
This concerns constant expressions first and the second allows a
narrowing in rare cases, of which the first line is one but the
"int i = 2.0" isn't.

Back to comp.lang.java.programmer | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: Possible loss of precision Michael Jung <miju@golem.phantasia.org> - 2013-11-14 20:39 +0100
  Re: Possible loss of precision Gene Wirchenko <genew@telus.net> - 2013-11-14 15:03 -0800
    Re: Possible loss of precision Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-11-14 18:31 -0500
      Re: Possible loss of precision Joerg Meier <joergmmeier@arcor.de> - 2013-11-15 00:55 +0100
      Re: Possible loss of precision Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-11-14 20:19 -0500
        Re: Possible loss of precision taqmcg@gmail.com - 2013-11-15 07:01 -0800
        Re: Possible loss of precision Martin Gregorie <martin@address-in-sig.invalid> - 2013-11-15 21:36 +0000
    Re: Possible loss of precision Michael Jung <miju@golem.phantasia.org> - 2013-11-15 19:24 +0100
      Re: Possible loss of precision Patricia Shanahan <pats@acm.org> - 2013-11-15 20:48 -0800
        Re: Possible loss of precision Michael Jung <miju@golem.phantasia.org> - 2013-11-17 13:28 +0100
          Re: Possible loss of precision Patricia Shanahan <pats@acm.org> - 2013-11-17 08:05 -0800

csiph-web