This C++ program generates calendars for a given month and year using the Gregorian calendar system. The program accepts user input to select the type of calendar to generate (yearly, monthly or check for leap year) and then prompts the user to enter the month and year.
For a monthly calendar, the program generates the calendar for all 12 months of the given year. The program first determines the number of days in the given month and year, and then calculates the day of the week for the first day of the month using a formula. The calendar is then outputted in a format that displays the days of the week and dates for each month.
For a yearly calendar, the program generates a calendar for the entire year by iterating over all 12 months and generating the corresponding calendar for each month.
To check if a given year is a leap year, the program prompts the user to enter the year and determines if it meets the criteria for being a leap year according to the Gregorian calendar system.
This program is written using basic functions of C++ and is documented with comments to improve code readability.