说明：  一个非常完整的动态数组类,包含一维数组,二维数组,3维数组. 具有常规构造函数,拷贝构造函数,付值函数,不存在内存泄露.
(a very comprehensive array of dynamic category, contains one-dimensional arrays, two-dimensional array, three-dimensional array. conventional structural function, the copy constructor function, pay-valued function, and there is no memory leakage.)