note 93675 added to functions.returning-values

rusty at socrates dot berkeley dot edu mentions variables getting unset when a function returns nothing. They're not unset in the strictest sense - they're assigned null. <?php function hasNoReturnValue() { //return null; } function hasNoReturnValueButReturns() { return/*null*/; } function returnsNull() { return null; } var_dump(hasNoReturnValue()); var_dump(hasNoReturnValueButReturns()); var_dump(returnsNull()); ?> All of those return NULL. isset() treats NULL-set Variables as unset, but there is a difference. While for most cases differentiation isn't necessary, it's worth noting that if you have a construct like <?php $arr[$key] = null; ?> Then <?php array_key_exists($key,$arr); ?> will evaluate as true, while <?php isset($arr[$key]); ?> will not. Unset variables var_dump as null, too; but only properly unset variables will ever throw an error relating to an unset variable - NULL-set variables will not. That doesn't invalidate the approach, mind you. isset() doesn't know the difference, so if that's the behaviour you want, go for it. ---- Server IP: 217.160.72.57 Probable Submitter: 80.153.202.193 ---- Manual Page -- http://www.php.net/manual/en/functions.returning-values.php Edit -- https://master.php.net/note/edit/93675 Del: integrated -- https://master.php.net/note/delete/93675/integrated Del: useless -- https://master.php.net/note/delete/93675/useless Del: bad code -- https://master.php.net/note/delete/93675/bad+code Del: spam -- https://master.php.net/note/delete/93675/spam Del: non-english -- https://master.php.net/note/delete/93675/non-english Del: in docs -- https://master.php.net/note/delete/93675/in+docs Del: other reasons-- https://master.php.net/note/delete/93675 Reject -- https://master.php.net/note/reject/93675 Search -- https://master.php.net/manage/user-notes.php