类继承的应用

使用关键字 extends

<?php
    class person{
        var $name;
        var $sex;
        var $age;

        function __construct($name='',$sex='男',$age=1){
            $this->name=$name;
            $this->age=$age;
            $this->sex=$sex;
        }

        function say(){
            echo '我的名字：',$this->name,'我的性别是',$this->sex,'我的年龄是',$this->age;
            echo '<br>';
        }

        function run(){
            echo $this->name,'正在走路';
            echo '<br>';
        }
    }

class stu extends person{
    var $school;

    function study(){
        echo $this->name,'正在',$this->school,'学习';
        echo '<br>';
    }
}

class teacher extends stu{
    var $wage;

    function teaching(){
        echo $this->name,'正在',$this->school,'教书','每月工资是',$this->wage;
    }
}

$teacher1= new teacher('张三','男',40);
$teacher1->school='edu';
$teacher1->wage=5000;

$teacher1->say();
$teacher1->run();
$teacher1->teaching();

/*
打印结果是：
我的名字：张三我的性别是男我的年龄是40
张三正在走路
张三正在edu教书每月工资是5000
*/

?>