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Re: Possible loss of precision

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Patricia Shanahan <pats@acm.org> writes:

> On 11/15/2013 10:24 AM, Michael Jung wrote:
>> Gene Wirchenko <genew@telus.net> writes:
>>> On Thu, 14 Nov 2013 20:39:42 +0100, Michael Jung
>>> <miju@golem.phantasia.org> wrote:
>>>> ram@zedat.fu-berlin.de (Stefan Ram) writes:
>> [...]
>>>>>    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?
>> Since compile-time constant expressions are FP-strict and could be done,
>> I guess it was seen as pathological and not worth the effort.
> I think the difference is that there is a cast-free way of
> initializing an int to the value 2.

Not if you wanted to do "int a = 2 * 0.5;" or something similar.

> On the other hand, without the special narrowing rule for
> initializers, there would be no cast-free way of initializing a byte
> with the value 2.

They could have spent a suffix "B/b" (for non-hex integer literals) as
with "l/L".

Michael

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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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