PHP: rfc:number_format_negative_zero

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====== PHP RFC: Prevent number_format() from returning negative zero ======
  * Version: 0.1
  * Date: 2017-04-01
  * Author: Craig Duncan <php@duncanc.co.uk>
  * Proposed version: PHP 7.2
  * Status: Implemented (in PHP 7.2)

===== Introduction =====

Calling ''number_format(-0.00)'' returns ''string(1) "0"'', however calling ''number_format(-0.01)'' returns ''string(2) "-0"''.

As ''number_format()'' is commonly used for formatting numbers for human-readable display, this behaviour is unexpected.

===== Proposal =====

This RFC proposes keeping ''number_format()'' consistent and not displaying the sign when a number is rounded to zero.

===== Concerns =====

There was an argument that all floating point logic in PHP follows IEEE 754, where negative zero is valid.

However ''number_format()'' already prevents negative zero, so this isn't the case.

===== Backward Incompatible Changes =====

This change has BC concerns for anybody relying on the current behaviour, but this is thought to be incredibly minor and not unrealistic for a point release.

===== Proposed PHP Version(s) =====

PHP 7.2

===== Proposed Voting Choices =====

Simple Yes/No vote that doesn't change the language itself so requires 50% + 1 votes to get 'accepted'. 

<doodle title="Prevent number_format() from returning negative zero" auth="duncan3dc" voteType="single" closed="true">
   * Yes
   * No
</doodle>

===== Implementation =====

Pull request:
https://github.com/php/php-src/pull/2508

=====References =====

Initial discussion that led to this RFC's creation:
https://externals.io/thread/522

Discussion thread:
https://externals.io/thread/800

Voting thread:
https://externals.io/thread/828
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