echo引用类值时，echo返回任何内容[关闭]

class bbsObj{
    var $num;
    var $dates;
    var $title;
    var $counts;
    function bbsObj($num, $datas, $title, $counts) {
        $this->num = $num;
        $this->dates = $num;
        $this->title = $title;
        $this->counts = $counts;        
    }

    function getNum(){
        return $this->num;
    }
    function getDates(){
        return $this->dates;
    }
}   

$bbsObject = new bbsObj("1", "2012", "title", "0");
$data = array();
$data[0] = $bbsObject;
echo($data[0]->getNum());

is there any way to express arraylist < class > type in php?

I believe echo should returns "1" but dont know why it returns nothing and shows nothing.

why am I getting nothing when I echoing?

Its outputting 1

Check it -- http://codepad.org/zRqQe8RX

Check your php version