{ $var++; } $c = 5; count_2($c); echo $c; // kết quả sẽ là 5 ?> <?php class cha { public $ten_cha = "toi la cha"; public function test() { echo $this->ten_cha . "<br />"; } } class con extends cha { public $ten_con = 'toi la con'; public function test() { parent::test(); //phuong thuc test la cua class cha echo $this->ten_con . "<br />"; } } $a = new con(); $a->test();