__isset () detects if the class internal variable is set

__isset ()--detects the existence of private variables within the class
　　Automatically executes when the Isset method is executed

Class per{private $name;　　Private $age;　　　　function __construct ($name, $age) {$this->name= $name;　　$this->age= $age;　　} function __isset ($var) {//Execute Isset method automatically executes return isset ($this, $var); }} $p =new Per (' Jack ', Var_dump); (Isset ($p->name)); If you do not set the __isset () Magic function error, outside the class is not accessible to private variables within the class

　　

__isset () detects if the class internal variable is set