Question

我试图用PHP自学OOP。我有一个儿童班的错误，有人知道为什么我会收到这个错误吗？

致命错误：在第28行的C：\ wamp \ www \ starter \ display.php中调用未定义的方法User :: getSkipper（）

User类是这样的：

<?php
class User
{
    protected $_first_name;
    protected $_last_name;
    protected $_email;

    public function __construct($first_name, $last_name, $email) 
    {
        $this->_first_name = $first_name;
        $this->_last_name = $last_name;
        $this->_email = $email;
    }

    public function getFirstName()
    {
        return $this->_first_name;
    }

    public function getLastName()
    {
        return $this->_last_name;
    }

    public function getEmail()
    {
        return $this->_email;
    }       
}

?>

船长课是这样的：

<?php
class Skipper extends User
{
    protected $_skipper;

    public function __construct($first_name, $last_name, $email, $skipper) 
    {
        $this->_skipper = $skipper;
    }

    public function getSkipper()
    {
        return $this->_skipper;
    }
}
?>

执行以下代码时抛出错误：

$user1 = new User('Steven', 'Smith', 'steve@sljgksdj.com', 'Yes');
echo '<p>First Name: ' . $user1->getFirstName() .'</p>';
echo '<p>Last Name: ' . $user1->getLastName() .'</p>';
echo '<p>Email: ' . $user1->getEmail() .'</p>';
echo '<p>Skipper: ' . $user1->getSkipper() .'</p>';

Answer 1

如果skipper扩展了User，则需要实例化Skipper。另外，我对于将“是”传递给Skipper构造函数时想要实现的目标感到困惑。

<?php
class User
{
    protected $_first_name;
    protected $_last_name;
    protected $_email;

    public function __construct($first_name, $last_name, $email) 
    {
    $this->_first_name = $first_name;
    $this->_last_name = $last_name;
    $this->_email = $email;
   }

   public function getFirstName()
   {
    return $this->_first_name;
    }

    public function getLastName()
   {
    return $this->_last_name;
    }

    public function getEmail()
   {
    return $this->_email;
    }       
};

<?php
class Skipper extends User
{
protected $_skipper;

    public function __construct($first_name, $last_name, $email, $skipper) 
   {
    parent::__construct($first_name, $last_name, $email) 
    $this->_skipper = $skipper;
    }

    public function getSkipper()
    {
    return $this->_skipper;
    }
}

$skipper1 = new Skipper('Steven', 'Smith', 'steve@sljgksdj.com', 'Yes');
echo '<p>First Name: ' . $skipper1->getFirstName() .'</p>';
echo '<p>Last Name: ' . $skipper1->getLastName() .'</p>';
echo '<p>Email: ' . $skipper1->getEmail() .'</p>';

Answer 2

您创建了一个类user的对象，而用户没有任何方法getSkipper。您应该创建类Skipper的对象。

$user1 = new Skipper('Steven', 'Smith', 'steve@sljgksdj.com', 'Yes');

致命错误：调用未定义的方法User :: getSkipper（）

2 个答案: