num_marked_dates is an integer containing the number of days that have a mark over them. marked_date is an array containing the day numbers that currently have a mark over them. month, year, and selected_day contain the currently visible month, year, and selected day respectively. All of these fields should be considered read only, and everything in this struct should only be modified using the functions provided below. Note Note that month is zero-based (i.e it allowed values are 0-11) while selected_day is one-based (i.e. allowed values are 1-31).