PHP RFC: Add 4 new rounding modes to round() function


The RFC proposes to add 4 new modes to the round() function.

Two first comments on the documentation page of the round() function are related to the missing modes of rounding. The first comment has an outstanding number of 309 votes.

Moreover, the NumberFormatter already implements 4 new proposed modes known as ROUND_CEILING, ROUND_FLOOR, ROUND_DOWN, ROUND_UP.


Adding 4 new constants for the rounding modes of function round():

  • PHP_ROUND_CEILING - rounds num to the nearest integer bigger than num,
  • PHP_ROUND_FLOOR - rounds num to the nearest integer lower than num,
  • PHP_ROUND_AWAY_FROM_ZERO - rounds num away from zero,
  • PHP_ROUND_TOWARD_ZERO - rounds num towards zero.

Backward Incompatible Changes


Proposed PHP Versions



Why not use functions ceil() and floor()?

The functions ceil() and floor() round numbers to the full integer, while the function round() rounds the number by given precision. Implementing new rounding modes we get equivalent of those functions using round() with 0 as precision.

ceil($number) === round($number, 0, PHP_ROUND_CEILING); //true
floor($number) === round($number, 0, PHP_ROUND_FLOOR); //true

Why not the names PHP_ROUND_UP and PHP_ROUND_DOWN?

Such constants already exist in the NumberFormatter and represent rounding modes 'away from zero' and 'toward zero'. However the names rounding up and down are ambiguous. They may be easily confused with the rounding ceiling/floor, while the terms away from/toward zero are distinct.

Proposed Voting Choices

As per the voting RFC a yes/no vote with a 2/3 majority is needed for this proposal to be accepted.

Voting started on 2023-09-x and will end on 2023-09-x.



Links to external references, discussions or RFCs

Rejected Features

Keep this updated with features that were discussed on the mail lists.

rfc/new_rounding_modes_to_round_function.txt · Last modified: 2023/09/04 22:14 by jorg_sowa