#31380 [NEW]: PHP logic problem

From: alex at arjomand dot net Operating system: Windows XP Pro PHP version: 4.3.10 PHP Bug Type: *General Issues Bug description: PHP logic problem Description: ------------ There is a problem with PHP's logic and string conventions. Currently, the comparison 0 == "alex" (or any arbitrary string) returns true. The comparison 0 == false also returns true, but the comparison "alex" == false returns false. This gives us the following logical fallacy: A == B, B == C, but A != C. The first comparison (0 == 'alex') is due to a PHP convention explained here: http://ca.php.net/manual/en/language.types.string.php#language.types.string.conversion The third comparison ("alex" == false) is due to an implicit PHP convention - that any non-empty string is true. These two conventions are inconsistent, and lead to the above errors. Under this system, PHP no longer has referential integrity. Reproduce code: --------------- <? echo (0 == false) === true; # returns true echo "<br>"; echo (0 == "alex") === true; # returns true echo "<br>"; echo ("alex" == false) === false; # returns false ?> -- Edit bug report at http://bugs.php.net/?id=31380&edit=1 -- Try a CVS snapshot (php4): http://bugs.php.net/fix.php?id=31380&r=trysnapshot4 Try a CVS snapshot (php5.0): http://bugs.php.net/fix.php?id=31380&r=trysnapshot50 Try a CVS snapshot (php5.1): http://bugs.php.net/fix.php?id=31380&r=trysnapshot51 Fixed in CVS: http://bugs.php.net/fix.php?id=31380&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=31380&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=31380&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=31380&r=needscript Try newer version: http://bugs.php.net/fix.php?id=31380&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=31380&r=support Expected behavior: http://bugs.php.net/fix.php?id=31380&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=31380&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=31380&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=31380&r=globals PHP 3 support discontinued: http://bugs.php.net/fix.php?id=31380&r=php3 Daylight Savings: http://bugs.php.net/fix.php?id=31380&r=dst IIS Stability: http://bugs.php.net/fix.php?id=31380&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=31380&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=31380&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=31380&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=31380&r=mysqlcfg