[RFC] [DISCUSSION] More precise float value
| From: | Yasuo Ohgaki | Date: | Fri, 04 Sep 2015 00:41:04 +0000 |
| Subject: | [RFC] [DISCUSSION] More precise float value | ||
| Groups: | php.internals | ||
| Request: | Send a blank email to internals+get-88042@lists.php.net to get a copy of this message | ||
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!
Regards,
--
Yasuo Ohgaki
yohgaki@ohgaki.net