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Groups > comp.lang.java.programmer > #26505

Re: Possible loss of precision

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On Thu, 14 Nov 2013 20:39:42 +0100, Michael Jung
<miju@golem.phantasia.org> wrote:

>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.

     Why isn't it though?

Sincerely,

Gene Wirchenko

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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

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