PHP in a Nutshell

Name

unset()

Synopsis

    void unset ( mixed var [, mixed var [, mixed ...]] )

The unset() function deletes a variable so that isset() will return false. Once deleted, you can recreate a variable later on in a script.

    $name = "Paul";
    if (isset($name)) print "Name is set\n";
    unset($name);
    if (isset($name)) print "Name is still set\n";

That would print out "Name is set", but not "Name is still set", because calling unset() has deleted the $name variable.