#50824 [NEW]: modulus (mod) returns wrong value

From: jancha at trave dot lv Operating system: Gentoo PHP version: 5.2.12 PHP Bug Type: Math related Bug description: modulus (mod) returns wrong value Description: ------------ We came accorss following case: <?php echo 72.6 * 100 % 100; You would expect: 60 But you get: 59 We did further analysis and got following results: [OK] 72.0:0 [FAIL] 72.1:9 [OK] 72.2:20 [OK] 72.3:30 [OK] 72.4:40 [OK] 72.5:50 [FAIL] 72.6:59 [OK] 72.7:70 [OK] 72.8:80 [OK] 72.9:90 That makes us think that bug happens, if last digit is either 1 or 6. Also, according to manual, operands of modulus are converted to integers by stripping decimal part away - in our case that is not reason, as 72.6 * 100 = 7260 (float). And conversion to int should result with 7260. Reproduce code: --------------- <?php echo 72.6 * 100 % 100; Expected result: ---------------- 60 Actual result: -------------- 59 -- Edit bug report at http://bugs.php.net/?id=50824&edit=1 -- Try a snapshot (PHP 5.2): http://bugs.php.net/fix.php?id=50824&r=trysnapshot52 Try a snapshot (PHP 5.3): http://bugs.php.net/fix.php?id=50824&r=trysnapshot53 Try a snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=50824&r=trysnapshot60 Fixed in SVN: http://bugs.php.net/fix.php?id=50824&r=fixed Fixed in SVN and need be documented: http://bugs.php.net/fix.php?id=50824&r=needdocs Fixed in release: http://bugs.php.net/fix.php?id=50824&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=50824&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=50824&r=needscript Try newer version: http://bugs.php.net/fix.php?id=50824&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=50824&r=support Expected behavior: http://bugs.php.net/fix.php?id=50824&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=50824&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=50824&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=50824&r=globals PHP 4 support discontinued: http://bugs.php.net/fix.php?id=50824&r=php4 Daylight Savings: http://bugs.php.net/fix.php?id=50824&r=dst IIS Stability: http://bugs.php.net/fix.php?id=50824&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=50824&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=50824&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=50824&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=50824&r=mysqlcfg