rfc:precise_float_value

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rfc:precise_float_value [2016/06/05 19:02] – Update voting choice bukkarfc:precise_float_value [2016/07/09 12:05] – this RFC has already been implemented cmb
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   * Date: 2015-07-30   * Date: 2015-07-30
   * Author: Yasuo Ohgaki <yohgaki@ohgaki.net>, Jakub Zelenka <bukka@php.net>   * Author: Yasuo Ohgaki <yohgaki@ohgaki.net>, Jakub Zelenka <bukka@php.net>
-  * Status: Under Discussion+  * Status: Implemented (PHP 7.1)
   * First Published at: http://wiki.php.net/rfc/precise_float_value   * First Published at: http://wiki.php.net/rfc/precise_float_value
  
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 This RFC is based on the discussion about displaying float values in json_encode and proposes more precise float value handling overall. This RFC is based on the discussion about displaying float values in json_encode and proposes more precise float value handling overall.
  
-JSON is used to exchange data between systems. Although [[https://tools.ietf.org/html/rfc7159|JSON RFC "6 Numbers"]]  does not require specific implementation for float/int type, float value should be handled as precise as possible by default. +JSON is used to exchange data between systems. Although [[https://tools.ietf.org/html/rfc7159|JSON RFC "6 Numbers"]] does not require specific implementation for float/int type, a float value should be handled as precise as possible by default.
  
-Currently, json_encode() uses EG(precision) which is set to 14. That means that 14 digits max are used for displaying (printing) the number. IEEE 754 double supports higher precision and serialize()/var_export() uses PG(serialize_precision)=17 to be more precise. Since json_encode() uses EG(precision), json_encode() removes lower digits of fraction parts and destroys original value even if PHP's float could hold more precise float value.+Currently json_encode() uses EG(precision) which is set to 14. That means that 14 digits at most are used for displaying (printing) the number. IEEE 754 double supports higher precision and serialize()/var_export() uses PG(serialize_precision) which set to 17 be default to be more precise. Since json_encode() uses EG(precision), json_encode() removes lower digits of fraction parts and destroys original value even if PHP's float could hold more precise float value.
  
 <code php> <code php>
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 ===== Proposal ===== ===== Proposal =====
  
-This RFC proposes to introduce EG(precision)=-1 and PG(serialize_precision)=-1 that uses zend_dtoa()'s mode 0 which uses better algorigthm for rounding float numbers (-1 is used to indicate 0 mode).+This RFC proposes to introduce a new setting EG(precision)=-1 and PG(serialize_precision)=-1 that uses zend_dtoa()'s mode 0 which uses better algorigthm for rounding float numbers (-1 is used to indicate 0 mode).
  
 The RFC also proposes changing ini for JSON precision to PG(serialize_precision). The RFC also proposes changing ini for JSON precision to PG(serialize_precision).
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-===== Proposed Voting Choices =====+===== Voting =====
  
-Requires a 2/3 majority+Requires a 2/3 majority for the first vote (mode 0 to become default for serialize precision) and 50%+1 majority for the second vote (changing default for json).
  
-There will be two votings+The both votes are straight Yes/No votes.
  
-  * whether to introduce mode 0 and use it as default for serialize_precision +<doodle title="Should mode 0 be introduced and set as default for PG(serialize_precision)" auth="bukka" voteType="single" closed="true"> 
-  * should PG(serialize_precision) be used instead of EG(precision) in json_encode.+   * Yes 
 +   * No 
 +</doodle> 
 + 
 +<doodle title="Should PG(serialize_precision) be used instead of EG(precision) in json_encode" auth="bukka" voteType="single" closed="true"> 
 +   * Yes 
 +   * No 
 +</doodle> 
 + 
 +The votes started on 2016-06-12 at 19:00 UTC and ended on 2016-06-19 at 19:00 UTC.
  
 ===== Patches and Tests ===== ===== Patches and Tests =====
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   * https://github.com/php/php-src/pull/1455   * https://github.com/php/php-src/pull/1455
  
-Note that the PR is currently outdate but it will be updated if the RFC is accepted.+Note that the PR is currently outdated but it will be updated if the RFC is accepted.
  
 ===== Implementation ===== ===== Implementation =====
 +
 +Merged into php-src for PHP 7.1: https://github.com/php/php-src/commit/75b86a2
 +
 After the project is implemented, this section should contain  After the project is implemented, this section should contain 
-  - the version(s) it was merged to 
-  - a link to the git commit(s) 
   - a link to the PHP manual entry for the feature   - a link to the PHP manual entry for the feature
  
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 ===== Rejected Features ===== ===== Rejected Features =====
-Keep this updated with features that were discussed on the mail lists.+ 
 +None
  
rfc/precise_float_value.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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