Introduction - If you have any usage issues, please Google them yourself
Customize a simple date class DateType, it has a data member y, m, d, is used to indicate the current date, month, and day. To achieve the latter design class (complete) function, and then design the appropriate class member functions. For example, the following is the " prototype" is used to achieve the increase of day, compare two date are equal, and the output of dates and other operations. Please complete all kinds of member functions, and prepare the main function, indicating DateType class object for each member function definition be called to verify their correctness.