编写一个程序，在循环结构中测试成员函数nextDate是否正常工作，要求每次循 环都输出日期。要保证能够测试出如下结果： a)能够进入下一个月。 b)能够进入下一年。-Write a program to test the member function nextDate is working in a cyclic structure, requiring each loop output date. Make sure it can test the following resu