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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: Draft


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.


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


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'.



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

rfc/number_format_negative_zero.1491060393.txt.gz · Last modified: 2017/09/22 13:28 (external edit)