#45518 [Opn->Bgs]: NULL matching zero, empty array, false

ID: 45518 User updated by: stephen dot cuppett at sas dot com Reported By: stephen dot cuppett at sas dot com -Status: Open +Status: Bogus Bug Type: Variables related Operating System: Windows XP/2003 PHP Version: 5.2.6 New Comment: NM, I see the loose comparisons table in the appendix. Previous Comments: ------------------------------------------------------------------------ [2008-07-15 12:19:28] stephen dot cuppett at sas dot com Description: ------------ I noticed a behavior with PHP 5.2.x that I found disturbing. PHP is matching variables initialized to zero, an empty array and false with NULL. From the documentation here: http://us2.php.net/NULL The only thing that should match NULL are ones that meet these criteria: A variable is considered to be null if: - it has been assigned the constant NULL. - it has not been set to any value yet. - it has been unset(). The function empty() should return true in the above cases (and does), but a comparison operator of == should not. FYI, is_null() returns false and the === operator works as expected too. Reproduce code: --------------- <?php $empty_array = array(); if ($empty_array == NULL) echo "Empty array, same as NULL\n"; else echo "Empty array, diff from NULL\n"; $zero = 0; if ($zero == NULL) echo "Zero, same as NULL\n"; else echo "Zero, different from NULL\n"; ?> Expected result: ---------------- Empty array, diff from NULL Zero, different from NULL Actual result: -------------- Empty array, same as NULL Zero, same as NULL ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=45518&edit=1