Bug #53989 [Opn->Bgs]: Notice: Undefined variable/index with xor, but not with or

Edit report at http://bugs.php.net/bug.php?id=53989&edit=1 ID: 53989 Updated by: felipe@php.net Reported by: martin at feredoras dot de Summary: Notice: Undefined variable/index with xor, but not with or -Status: Open +Status: Bogus Type: Bug Package: Scripting Engine problem Operating System: Tested only with Windows PHP Version: 5.3.5 Block user comment: N Private report: N New Comment: This is because the OR logical expression doesn't requires the right expression to be executed when the first expression is evaluated to true. But XOR requires. Previous Comments: ------------------------------------------------------------------------ [2011-02-11 03:18:08] martin at feredoras dot de Description: ------------ I want to check, if a variable is not set. If the variable is not set, i want to check, if this variable has a special value. There is no problem with "or", but with "xor" outputs a notice. Test script: --------------- <? session_start(); if(!isset($_SESSION['foo']) xor $_SESSION['foo'] == 1) echo "foo"; if(!isset($bar) xor $bar== 1) echo "bar"; if(!isset($_SESSION['foo']) or $_SESSION['foo'] == 1) echo "foo"; if(!isset($bar) or $bar== 1) echo "bar"; ?> Expected result: ---------------- foobarfoobar Actual result: -------------- Notice: Undefined index: foo in C:\xampp\htdocs\feredoras\testing.php on line 4 foo Notice: Undefined variable: bar in C:\xampp\htdocs\feredoras\testing.php on line 5 barfoobar ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=53989&edit=1