NULL
The special NULL value represents a variable with no value. NULL is the only possible value of type NULL.
Note: The null type was introduced in PHP 4.
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().
Syntax
There is only one value of type null, and that is the case-insensitive keyword NULL.
<?php
$var = NULL;
?>
Casting to NULL
Casting a variable to null will remove the variable and unset its value.