摘要： 1 class Vector2D 2 { 3 private $_x; 4 private $_y; 5 6 /** 7 * Constructor. 8 */ 9 public function __construct($x = 0, $y = 0)10 {11 $this->_x = $x;12 $this->_y = $y;13 }14 15 /**16 * Generates a copy of $this vector.17 * @return Vector2D A copy of $this vector.18 */19 public function mycopy() 阅读全文