新人学习PHP问题，发现书上代码不对
在书上发现一段代码，敲下来后发现不对。。
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<?php
class Person
{
private $name;
private $sex;
private $age;
function __construct($name="",$sex="男",$age=23)
{
$this->name=$name;
$this->sex=$sex;
$this->age=$age;
}
function say()
{
echo "我的名字 ".$this->name."，性别 ".$this->sex."，年龄 ".$this->age."<br>";
}
function run()
{
echo $this->name."正在走路<br>";
}
}
class Student extends Person
{
var $school;
function study()
{
echo $this->name."正在".$this->school."学习<br>";
}
}
class Teacher extends Student
{
var $wage;
function teaching()
{
echo $this->sex."正在".$this->school."教学，每个月工资为".$this->wage."<br>";
}
}
$teacher1=new Teacher("张三","男",40);
$teacher1->school="沈阳工学院";
$teacher1->wage=3000;
$teacher1->say();
$teacher1->run();
$teacher1->teaching();
?>
