php对象上的相同类属性

Is it possible for a PHP class to store an object of the same class? Or is there some way to implement this behaviour? In c++ it is possible with pointers but there are no pointers in PHP.

Yes, it is possible. Check this example :

class Obj {

    private $obj ;

    public function setObject($obj) {
        $this->obj = $obj ;
    }

    public function createAnother() {
        return new Obj();
    }

    public function createOwnObject() {
        $this->obj = new Obj();
    }

}

$obj1 = new Obj ;

$obj2 = new Obj ;
$obj2->setObject($obj1) ;

$obj3 = $obj2->createAnother() ;