Bug #78294 [NEW]: Unexpected lose equality result

From: iuli dot butuc at yahoo dot com Operating system: Windows 10 PHP version: Irrelevant Package: *Math Functions Bug Type: Bug Bug description:Unexpected lose equality result Description: ------------ Tested on php versions >= 5.6. The lose equality result for '201905025815311.33' == '201905025815311.34' is true for some reason i cannot identify. Needless to say using using the === operator fixes the issue. But the result for me is strange. Those strings are probably stored as floats in memory because they have a perfect valid float format. But the float comparison for 201905025815311.33 == 201905025815311.34 fails as well(evaluates to true). Even if the numbers are rounded, it does not explain how can give the right result for 201905025815311.33 == 201905025815311.32 which should have the same "rounding" rules as 201905025815311.33 == 201905025815311.34. Maybe the 1.33 ending is the problem, but does not ring a bell to me from a mathematical perspective. Dumping the PHP_FLOAT_MAX constant on php versions that have it (7.2+) suggest that php should not have any trouble working with these numbers. Test script: --------------- var_dump('201905025815311.33' == '201905025815311.34'); var_dump('201905025815311.33' == '201905025815311.32'); var_dump(201905025815311.33 == 201905025815311.34); var_dump(201905025815311.33 == 201905025815311.32); var_dump(201905025815311.32); var_dump(201905025815311.33); var_dump(201905025815311.34); var_dump(PHP_FLOAT_MAX); Expected result: ---------------- bool(false) bool(false) bool(false) bool(false) float(2.0190502581531E+14) float(2.0190502581531E+14) float(2.0190502581531E+14) float(1.7976931348623E+308) Actual result: -------------- bool(true) bool(false) bool(true) bool(false) float(2.0190502581531E+14) float(2.0190502581531E+14) float(2.0190502581531E+14) float(1.7976931348623E+308) -- Edit bug report at https://bugs.php.net/bug.php?id=78294&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=78294&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=78294&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=78294&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=78294&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=78294&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=78294&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=78294&r=needscript Try newer version: https://bugs.php.net/fix.php?id=78294&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=78294&r=support Expected behavior: https://bugs.php.net/fix.php?id=78294&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=78294&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=78294&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=78294&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=78294&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=78294&r=dst IIS Stability: https://bugs.php.net/fix.php?id=78294&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=78294&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=78294&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=78294&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=78294&r=mysqlcfg