Doc #55164 [Ana]: Unclear/incorrect description of "casting to null"

Edit report at https://bugs.php.net/bug.php?id=55164&edit=1 ID: 55164 User updated by: deceze at gmail dot com Reported by: deceze at gmail dot com Summary: Unclear/incorrect description of "casting to null" Status: Analyzed Type: Documentation Problem Package: Documentation problem PHP Version: Irrelevant Block user comment: N Private report: N New Comment: Yes, but: error_reporting(E_ALL); var_dump($undefined); $foo = 'bar'; $foo = (unset)$foo; // or $foo = null var_dump($foo); unset($foo); var_dump($foo); Outputs: Notice: Undefined variable: undefined NULL NULL Notice: Undefined variable: foo NULL null is the default value for undefined variables, but undefined/"removed" variables are not the same as variables with a null value. Previous Comments: ------------------------------------------------------------------------ [2011-07-08 21:47:26] philip@php.net Simply this: <?php var_dump($undefined); ?> Outputs NULL. ------------------------------------------------------------------------ [2011-07-08 21:40:14] deceze at gmail dot com $b = (unset)$a in itself is quite weird, since it doesn't unset either $a or $b, it just assigns null to $b. ------------------------------------------------------------------------ [2011-07-08 21:35:45] philip@php.net I agree there is a bug here, but you can cast something to null using (unset) so: $a = "foo"; $b = "bar"; $b = (unset) $a; var_dump($b); NULL Slightly odd that it's (unset) and not (null) but it is what it is. That section should refer to the (unset) documentation within the type juggling documentation. ------------------------------------------------------------------------ [2011-07-08 21:18:01] deceze at gmail dot com Description: ------------ The documentation at http://www.php.net/manual/en/language.types.null.php states: "Casting a variable to null will remove the variable and unset its value." This seems incorrect and/or misleading. "Casting" to null is not possible as such through the cast syntax (null). Setting the type of a variable using settype($foo, 'null') or assigning null to any variable will not "remove" the variable. The variable continues to exist with the value null. Test script: --------------- // the documentation suggests something like this: $foo = 'bar'; settype($foo, 'null'); echo $foo; // PHP Notice: Undefined variable: foo // actual behavior: $foo = 'bar'; settype($foo, 'null'); echo $foo; // empty output, no warning ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=55164&edit=1