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Date: Mon, 30 May 2016 17:34:10 +0100
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To: "internals@lists.php.net" <internals@lists.php.net>
Cc: Yasuo Ohgaki <yohgaki@ohgaki.net>
Content-Type: multipart/alternative; boundary=001a113fcd6c73b19d053411d372
Subject: Re: [PHP-DEV] [RFC] [DISCUSSION] More precise float value
From: bukka@php.net (Jakub Zelenka)

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On Fri, Sep 4, 2015 at 1:41 AM, Yasuo Ohgaki <yohgaki@ohgaki.net> wrote:

> Hi all,
>
> IEEE 754 double cannot express exact float values. That said,
> float values expressed by json/serialize/var_export/echo/print
> are not precise enough in many cases.
>
> Issues:
>  - json_encode() uses EG(precision)=14 that truncates float values.
> echo()/print()
>    does this as well.
>  - large EG(precision)/PG(serialize_precision) prints meaningless values.
>
> This RFC proposes zend_dtoa()'s 0 mode support which rounds float value
> to nearest value.
>
> https://wiki.php.net/rfc/precise_float_value
> https://github.com/php/php-src/pull/1455
>
> This change is simple enough for PHP 7.0. IMO.
> Comments/suggestions are appreciated!
>
>
Hi,

After asking Yasuo, I'm putting forward this RFC to have more precise float
to string decoding at least in PHP 7.1. I cleaned the RFC up a little bit
and it's targeting just 7.1.

It has been some time since this was announced so I will keep it open for a
week or two and then plan to start vote.

Cheers

Jakub

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