用类定义一个双向链表，并定义双向链表的排序插入，删除和输出操作的成员函数，可以实现依据姓名查找结点及修改结点数据的功能，把记录以通讯录形式保存在磁盘上。-Class definition with a two-way linked list, and define the order of two-way linked list insert, delete, and member functions of the output operation can be achieved based o