C语言实现的城市数据库系统，采用了链表的方法，可以查询，删除，添加城市信息，及以某城市为定点，它周围一定范围内的所有城市信息。-C language implementation of the urban database system, using the list method, you can query, delete, add city information, and to a city as a place, it all within a certain range around