面向对象PHP（二）

<code><span><span><?php </span><span>/**
*   1.子类与父类方法相同可以对父类方法重写
*   2.如果不希望父类被重写，用final关键字修饰，可以修饰类中方法，也可以是一个类（该类所有方法均不能被重写）
*/</span>header(<span>"Content-Type: text/html; charset=utf-8"</span>);<span>//去除中文乱码</span><span>final</span><span><span>class</span><span>BaseClass</span>{</span><span>final</span><span>public</span><span><span>function</span><span>test</span><span>()</span>{</span><span>echo</span><span>"BaseClass::test called.<br>"</span>;
    }
    <span>public</span><span><span>function</span><span>test1</span><span>()</span>{</span><span>echo</span><span>"BaseClass::test1 called.<br>"</span>;
    }
}
<span><span>class</span><span>ChildClass</span><span>extends</span><span>BaseClass</span>
    {</span><span>public</span><span><span>function</span><span>test</span><span>(<span>$value</span>=null)</span>{</span><span>//没有默认值会报错</span><span>echo</span><span>"ChildClass::test called "</span>.<span>$value</span>.<span>"<br>"</span>;
        }
    }

<span>$obj</span>=<span>new</span> ChildClass();
<span>$obj</span>-&gt;test(<span>"'222'"</span>);
<span>$obj</span>-&gt;test1();


<span>?&gt;</span></span></span></code>