class father
{
protected $salutation = "hello there!"; //問候

public function getsalutation()
{
print("$this-＞salutationn");
$this-＞identify();
}

protected function identify()
{
print("i am father.
n");
}
};

class son extends father
{
protected $salutation = "hey!"; //父類中的protected $salutation 被覆寫

protected function identify() //父類中的protected identify() 被覆寫
{
print("i am son.
n");
}
};

$obj = new son();
$obj-＞getsalutation(); //輸出hey! i am son.
?＞

//注: 在子類中沒有覆寫getsalutation()，但實際上仍然存在一個getsalutation().這個類中的$salutation和identify()
//與son子類的實例中的getsalutation()方法動態綁定，所以調用son的實例的getsalutation()方法，
//將調用son類中的成員salutation及identify()，而不是父類中的成員salutation及identify().

class father
{
private $salutation = "hello there!";

public function getsalutation()
{
print("$this-＞salutationn");
$this-＞identify();
}

private function identify()
{
print("i am father.
n");
}
}

class son extends father
{
private $salutation = "hey!";
private function identify()
{
print("i am son.
n");
}
}

$obj = new son();
$obj-＞getsalutation(); //輸出hello there! i am father.
?＞

class user //用戶
{
protected function isauthorized() //是否是驗證用戶
{
return(false);
}

public function getname() //獲得名字
{
return($this-＞name);
}

public function deleteuser($username) //刪除用戶
{
if(!$this-＞isauthorized())
{
print("you are not authorized.
n");
return(false);
}

//delete the user
print("user deleted.
n");
}
}

class authorizeduser extends user //認證用戶
{
protected function isauthorized() //覆寫isauthorized()
{
return(true);
}
}

$user = new user;
$admin = new authorizeduser;

//not authorized
$user-＞deleteuser("zeev");

//authorized
$admin-＞deleteuser("zeev");
?＞