protected

<?php

/**
 * Created by IntelliJ IDEA.
 * User: Administrator
 * Date: 2017/1/21
 * Time: 14:16
 * public,private,protected的区别
 *public:权限是最大的，可以内部调用，实例调用等。
 *protected: 受保护类型，用于本类和继承类调用。
 *private: 私有类型，只有在本类中使用。
 */
error_reporting(E_ALL);

class test{
    public $public;
    private $private;
    protected $protected;
    static $instance;
    public  function __construct(){
        $this->public    = 'public     <br>';
        $this->private   = 'private    <br>';
        $this->protected = 'protected  <br>';
    }
    static function tank(){
        if (!isset(self::$instance[get_class()]))
        {
            $c = get_class();
            self::$instance = new $c;
        }
        return self::$instance;
    }
    public function pub_function() {
        echo "you request public function<br>";
        echo $this->public;
        echo $this->private;        //private,内部可以调用
        echo $this->protected;      //protected,内部可以调用
        $this->pri_function();      //private方法，内部可以调用
        $this->pro_function();      //protected方法，内部可以调用
    }
    protected  function pro_function(){
        echo "you request protected function<br>";
    }
    private function pri_function(){
        echo "you request private function<br>";
    }
}
$test = test::tank();
echo $test->public;
echo $test->private;    //Fatal error: Cannot access private property test::$private
echo $test->protected;  //Fatal error: Cannot access protected property test::$protected
$test->pub_function();
$test->pro_function();  //Fatal error: Call to protected method test::pro_function() from context
$test->pri_function();  //Fatal error: Call to private method test::pri_function() from context