Bug #78073 [PATCH]: echo fmod(25, 0.2); // 0.2, must be 0

Edit report at https://bugs.php.net/bug.php?id=78073&edit=1 ID: 78073 Patch added by: e.grinec@gmail.com Reported by: e dot grinec at gmail dot com Summary: echo fmod(25, 0.2); // 0.2, must be 0 Status: Open Type: Bug Package: *Math Functions Operating System: Windows 10 x64 PHP Version: 7.3.5 Block user comment: N Private report: N New Comment: The following patch has been added/updated: Patch Name: patch.txt Revision: 1558951136 URL: https://bugs.php.net/patch-display.php?bug=78073&patch=patch.txt&revision=1558951136 Previous Comments: ------------------------------------------------------------------------ [2019-05-27 09:51:43] e dot grinec at gmail dot com Description: ------------ --- From manual page: https://php.net/function.fmod --- PHP 5.2.x through PHP 7.3.2 still the same problem. Code: <?php echo fmod(-25, 0.2); // -0.2, should be 0 echo -25 - floor(-25/0.2) * 0.2; // 0, as it should be ?> Default installation of OSPanel (OpenServer 5.2.2) with default configuration of php.ini and etc in it. Documentation says: "Returns the floating point remainder of dividing the dividend (x) by the divisor (y). The remainder (r) is defined as: x = i * y + r, for some integer i. If y is non-zero, r has the same sign as x and a magnitude LESS than the magnitude of y." But r magnitude EQUAL to y. Solution: function fmod($x, $y){return echo $x - floor($x/$y) * $y;} Test script: --------------- <?php echo var_dump(fmod(21, 0.2) == 0); // bool(false) echo var_dump(fmod(1, 0.1) == 0); // bool(false) echo fmod(1, 0.1); // 0.1 echo fmod(1, 0.2); // 0.2 Expected result: ---------------- <?php echo var_dump(fmod(21, 0.2) == 0); // bool(true) echo var_dump(fmod(1, 0.1) == 0); // bool(true) echo fmod(1, 0.1); // 0 echo fmod(1, 0.2); // 0 Actual result: -------------- bool(false) bool(false) 0.1 0.2 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=78073&edit=1