note 103060 added to function.isset

1) Note that isset($var) doesn't distinguish the two cases when $var is undefined, or is null. Evidence is in the following code. <?php unset($undefined); $null = null; if (true === isset($undefined)){echo 'isset($undefined) === true'} else {echo 'isset($undefined) === false'); if (true === isset($null)){echo 'isset($null) === true'} else {echo 'isset($null) === false'); ?> 2) If you want to distinguish undefined variable with a defined variable with a null value, then use array_key_exist <?php unset($undefined); $null = null; if (true !== array_key_exists('undefined', get_defined_vars())) {echo '$undefined doesnot exist';} else {echo '$undefined exists';} if (true === array_key_exists('null', get_defined_vars())) {echo '$null exist';} else {echo '$null doesnot exist';} ?> ---- Server IP: 69.147.83.197 Probable Submitter: 80.113.160.213 ---- Manual Page -- http://www.php.net/manual/en/function.isset.php Edit -- https://master.php.net/note/edit/103060 Del: integrated -- https://master.php.net/note/delete/103060/integrated Del: useless -- https://master.php.net/note/delete/103060/useless Del: bad code -- https://master.php.net/note/delete/103060/bad+code Del: spam -- https://master.php.net/note/delete/103060/spam Del: non-english -- https://master.php.net/note/delete/103060/non-english Del: in docs -- https://master.php.net/note/delete/103060/in+docs Del: other reasons-- https://master.php.net/note/delete/103060 Reject -- https://master.php.net/note/reject/103060 Search -- https://master.php.net/manage/user-notes.php