Bug #78172 [Opn->Nab]: Wrong rounding up/down when decimal places are specified

Edit report at https://bugs.php.net/bug.php?id=78172&edit=1 ID: 78172 Updated by: cmb@php.net Reported by: vecera at zdenekvecera dot cz Summary: Wrong rounding up/down when decimal places are specified -Status: Open +Status: Not a bug Type: Bug Package: *Math Functions Operating System: Windows, Linux PHP Version: 7.1.30 -Assigned To: +Assigned To: cmb Block user comment: N Private report: N New Comment: Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php It's like @danack said; IOW the PHP_ROUND_HALF_* constants are only relevant when the fractional part of $val * 10**$precision is exactly 0.5. Previous Comments: ------------------------------------------------------------------------ [2019-06-16 17:00:41] danack@php.net I don't understand what how you get your expected values. // round(1.44444, 3, PHP_ROUND_HALF_UP) (correct value: 1.445) That would be the same as expected 0.00044 rounded to 3 digits to be 0.001. but 0.00044 is less than 0.0005 which is the halfway point to 0.001. Similarly 0.00055 rounded to 3 figures is going to be 0.001 no matter the rounding. ------------------------------------------------------------------------ [2019-06-16 16:18:00] vecera at zdenekvecera dot cz Description: ------------ var_dump(round(1.44444, 3, PHP_ROUND_HALF_DOWN)); // float(1.444) OK var_dump(round(1.55555, 3, PHP_ROUND_HALF_DOWN)); // float(1.556) BUG (correct value: 1.555) var_dump(round(1.77777, 3, PHP_ROUND_HALF_DOWN)); // float(1.778) BUG (correct value: 1.777) var_dump(round(1.44444, 3, PHP_ROUND_HALF_UP)); // float(1.444) BUG (correct value: 1.445) var_dump(round(1.55555, 3, PHP_ROUND_HALF_UP)); // float(1.556) OK var_dump(round(1.77777, 3, PHP_ROUND_HALF_UP)); // float(1.778) OK // PHP version: 7.0.33, 7.1.30, 7.2.19, 7.3.6 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=78172&edit=1