php class中public,private,protected的区别以及实例分析
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2020-12-19
03:30:21
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php class中中public,private,protected的区别以及实例分析的区别以及实例分析
一，一，public,private,protected的区别的区别
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。
二，实例二，实例
复制代码 代码如下:
<?php
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
?>
从上面的例子中，我们可以看出，
public: 可以class内部调用，可以实例化调用。
private: 可以class内部调用，实例化调用报错。
protected： 可以class内部调用，实例化调用报错。
复制代码 代码如下:
<?php
class test{
public $public;
private $private;
protected $protected;
static $instance;
public function __construct(){
$this->public = ‘public <br>’;
$this->private = ‘private <br>’;
$this->protected = ‘protected <br>’;
}
protected function tank()
{
//私有方法不能继承，换成public,protected
if (!isset(self::$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;
}
protected 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();
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