PHP public访问修饰符
示例：
<?php
header("content-type:text/html;charset=utf-8");
// BaseClass
class pub {
public $tag_line = "软件开发网！";
function display() {
echo $this->tag_line."<br>";
}
}
// 子类
class child extends pub {
function show(){
echo $this->tag_line;
}
}
// 对象声明
$obj= new child;
// 输
