Introduction - If you have any usage issues, please Google them yourself
Defined date type Date. Requirements: (1) contains data members (date) provide a default constructor with month, day argument constructor and copy constructor define the set member function can set the date date plus one day operation defined intput member function, input date information, the input format is " YYYY-MM-DD" definition of member function print the output of dates. (2) write a complete program can be run, construct three types of objects date, and output the corresponding date information. (3) to achieve an object of type date subtraction.