Introduction - If you have any usage issues, please Google them yourself
(1) calendar display function. It can be initialized according to the system date. If there is no input, the calendar of the month of the system's date is displayed.
(2) calendar query, leap year judgment function. Enter the date to query, display the date of the month in which the query date is located, and also show whether the year is a leap year
(3) parameter check function. If the input date is illegal, the query will be rejected and the prompt information will be displayed.
(4) adjust the year, month and date, and display the adjusted date and calendar.