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

從上面的例子中，我們可以看出，
public: 可以class內部調用，可以實例化調用。
private: 可以class內部調用，實例化調用報錯。
protected：可以class內部調用，實例化調用報錯。

復制代碼代碼如下:

<?php
class test{
 public $public;
 private $private;
 protected $protected;
 static $instance;
 public&nbsp; function __construct(){
 $this->public&nbsp;&nbsp;&nbsp; = 'public&nbsp;&nbsp;&nbsp;&nbsp; <br>';
 $this->private&nbsp;&nbsp; = 'private&nbsp;&nbsp;&nbsp; <br>';
 $this->protected = 'protected&nbsp; <br>';
 }
 protected function tank(){&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; //私有方法不能繼承，換成public,protected
 if (!isset(self::$instance[get_class()]))
 {
 $c = get_class();
 self::$instance = new $c;
 }
 return self::$instance;
 }&nbsp;&nbsp; &nbsp;
 public function pub_function() {
 echo "you request public function<br>";
 echo $this->public;
 }
 protected&nbsp; function pro_function(){
 echo "you request protected function<br>";
 echo $this->protected;
 }
 private function pri_function(){
 echo "you request private function<br>";
 echo $this->private;
 }
}
class test1 extends test{
 public function __construct(){
 parent::tank();
 parent::__construct();
 }
 public function tank(){
 echo $this->public;
 echo $this->private;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; //Notice: Undefined property: test1::$private
 echo $this->protected;
 $this->pub_function();
 $this->pro_function();
 $this->pri_function();&nbsp;&nbsp;&nbsp; //Fatal error: Call to private method test::pri_function() from context 'test1'
 }
 public&nbsp; function pro_extends_function(){
 echo "you request extends_protected function<br>";
 }
 public function pri_extends_function(){
 echo "you request extends_private function<br>";
 }
}
error_reporting(E_ALL);
$test = new test1();
$test -> tank();&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; //子類和父類有相同名字的屬性和方法，實例化子類時，子類的中的屬性和方法會蓋掉父類的。
?>

從上面的例子中，我們可以看出，
public:    test中的public可以被繼承。
private:   test中的private不可以被繼承。
protected：test中的protected可以被繼承。
static：   test中的static可以被繼承。
唉，對于這些東西，老是不喜歡記著，用的時候，總感覺不對，又要去查，所以寫個例子，方便自己查看。

您可能感興趣的文章: