Craig Duncan

Craig Duncan


PHP RFC: Prevent number_format() from returning negative zero

  • Version: 0.1
  • Date: 2017-04-01
  • Author: Craig Duncan
  • Proposed version: PHP 7.2
  • Status: Implemented (in PHP 7.2)


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



Initial discussion that led to this RFC's creation:

Discussion thread:

Voting thread:


An option needs 50%+1 votes to win

Prevent number_format() from returning negative zero (93.3% approved)
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ashnazg Yes
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