Bug #81697 [NEW]: Since 8.0, php is not multiplying float values correctly

From: neil+php at neilmasters dot co dot uk Operating system: linux, mac PHP version: 8.0.13 Package: Math related Bug Type: Bug Bug description:Since 8.0, php is not multiplying float values correctly Description: ------------ Hi folks, I tried a searching prior to submitting because I can not see myself being the only person to have come across this, apologies if it is a duplicate. I also have to admit to not really knowing what it is I need to look for. I am seeing odd results when multiplying specific values since 8.0 on linux and mac - I can not test on windows currently. 2114.20 * 100: 211420 right? no. According to PHP since 8.0 it is 211419.99999999997 1.15 * 100: 115 yes? no. It results in 114.99999999999999 1.08 * 100: 108? Yes actually :) This does not seem to be an issue with ints, just floats. https://3v4l.org/rnTis is a quick 3v4l with a few examples and I have attached a test script which you can use to highlight the issue across any number range you want. Test script: --------------- <?php /** * Test script to demo the issue of multiplication of specific numbers * results in the wrong value. * * Using start of 1 and stop of 2 multiply every 2dp value(i.e. 1.01 - 1.99) by * 100 and var dump the value. * * Example results: * 1.06: 106 * 1.07: 107 * 1.08: 108 * 1.09: 109.00000000000001 * 1.10: 110.00000000000001 * 1.11: 111.00000000000001 * 1.12: 112.00000000000001 * 1.13: 112.99999999999999 * 1.14: 113.99999999999999 * 1.15: 114.99999999999999 * 1.16: 115.99999999999999 * 1.17: 117 * 1.18: 118 * ... * * Now here is the barking mad weirdness... bump up that start and stop by 1 and you get * totally different results, showing a lack of consistency in its wrongness. * * 2.00: 200 * 2.01: 200.99999999999997 * 2.02: 202 * 2.03: 202.99999999999997 * ... */ $start = 1; $stop = 2; for ($i = $start; $i < $stop; $i++) { for ($j = 0; $j < 100; $j++) { $number = (float)sprintf( '%s.%s', $i, $j < 10 ? sprintf('0%s', $j) : $j ); var_dump($number * 100); echo PHP_EOL; } } Expected result: ---------------- float(100) float(101) float(102) float(103) float(104) float(105) float(106) float(107) float(108) float(109) float(110) float(111) float(112) float(113) float(114) float(115) float(116) float(117) float(118) float(119) float(120) float(121) float(122) float(123) float(124) float(125) float(126) float(127) float(128) float(129) float(130) float(131) float(132) float(133) float(134) float(135) float(136) float(137) float(138) float(139) float(140) float(141) float(142) float(143) float(144) float(145) float(146) float(147) float(148) float(149) float(150) float(151) float(152) float(153) float(154) float(155) float(156) float(157) float(158) float(159) float(160) float(161) float(162) float(163) float(164) float(165) float(166) float(167) float(168) float(169) float(170) float(171) float(172) float(173) float(174) float(175) float(176) float(177) float(178) float(179) float(180) float(181) float(182) float(183) float(184) float(185) float(186) float(187) float(188) float(189) float(190) float(191) float(192) float(193) float(194) float(195) float(196) float(197) float(198) float(199) Actual result: -------------- float(100) float(101) float(102) float(103) float(104) float(105) float(106) float(107) float(108) float(109.00000000000001) float(110.00000000000001) float(111.00000000000001) float(112.00000000000001) float(112.99999999999999) float(113.99999999999999) float(114.99999999999999) float(115.99999999999999) float(117) float(118) float(119) float(120) float(121) float(122) float(123) float(124) float(125) float(126) float(127) float(128) float(129) float(130) float(131) float(132) float(133) float(134) float(135) float(136) float(137) float(138) float(139) float(140) float(141) float(142) float(143) float(144) float(145) float(146) float(147) float(148) float(149) float(150) float(151) float(152) float(153) float(154) float(155) float(156) float(157) float(158) float(159) float(160) float(161) float(162) float(163) float(164) float(165) float(166) float(167) float(168) float(169) float(170) float(171) float(172) float(173) float(174) float(175) float(176) float(177) float(178) float(179) float(180) float(181) float(182) float(183) float(184) float(185) float(186) float(187) float(188) float(189) float(190) float(191) float(192) float(193) float(194) float(195) float(196) float(197) float(198) float(199) -- Edit bug report at https://bugs.php.net/bug.php?id=81697&edit=1 -- Fix committed: https://bugs.php.net/fix.php?id=81697&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=81697&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=81697&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=81697&r=needscript Try newer version: https://bugs.php.net/fix.php?id=81697&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=81697&r=support Expected behavior: https://bugs.php.net/fix.php?id=81697&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=81697&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=81697&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=81697&r=globals PHP version support discontinued: https://bugs.php.net/fix.php?id=81697&r=phptooold Daylight Savings: https://bugs.php.net/fix.php?id=81697&r=dst IIS Stability: https://bugs.php.net/fix.php?id=81697&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=81697&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=81697&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=81697&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=81697&r=mysqlcfg