在子类中怎么使用父类中定义的第三方的类方法呢

<?php<br />class a {<br />	var $c;<br />	function aa() {<br />		echo "I'm a!";<br />	}<br />	function gc(){<br />		$this->c = new c;<br />	}<br />}<br />class b extends a {<br />	function bb() {<br />		echo "I'm b!";<br />	}<br />	function dc(){<br />		$this->c->c();//报错： Call to a member function c() on a non-object<br />		//在子类中如何使用父类中定义的第三方的类方法呢？<br />	}<br />}<br />class c {<br />	function c() {<br />		echo "I'm c!";<br />	}<br />}<br />$a = new a;<br />$b = new b;<br />$a->aa();//I'm a!<br />$a->gc();//I'm c!<br />$b->dc();//报错： Call to a member function c() on a non-object<br />?>

<br />class a {<br />    var $c;<br />    function aa() {<br />        echo "I'm a!";<br />    }<br />    function gc(){<br />        $this->c = new c;<br />    }<br />}<br />class b extends a {<br />    function bb() {<br />        echo "I'm b!";<br />    }<br />    function dc(){<br />		parent::gc();//要先实例化c $this->c才有值<br />		//由于 方法c() 和类c 同名，实例化时会自动调用（构造方法） 输出第三个I'm c!<br />        $this->c->c();//调用方法c() ,输出I'm c!<br />        <br />    }<br />}<br />class c {<br />    function c() {<br />        echo "I'm c!";<br />    }<br />}<br />$a = new a;<br />$b = new b;<br />$a->aa();//I'm a!<br />$a->gc();//I'm c!<br />$b->dc();//报错： Call to a member function c() on a non-object<br />//I'm a!I'm c!I'm c!I'm c!<br />

<br /><?php<br />class a {<br />    public $c;<br />    function aa() {<br />        echo "I'm a!";<br />    }<br />    function gc(){<br />        $this->c = new c;<br />    }<br />}<br />class b extends a {<br />    function bb() {<br />        echo "I'm b!";<br />    }<br />    function dc(){<br />        $this->gc(); // 执行gc方法创建c对象<br />        $this->c->c();<br />    }<br />}<br />class c {<br />    function c() {<br />        echo "I'm c!";<br />    }<br />}<br />$a = new a;<br />$b = new b;<br />$a->aa();//I'm a!<br />$a->gc();//I'm c!<br />$b->dc();//I'm c!<br />?><br />