Date_Calc is a calendar class used to calculate and manipulate calendar dates and retrieve dates in a calendar format. It does not rely on 32-bit system date stamps, so you can display calendars and compare dates that date pre 1970 and post 2038. Some of Date_Calc's features: comparing number of days between arbitrary dates, validating dates, calculating leap years, calculating the day of the week, calculating week of the year, calculating first and last days of the month, calculating next/prev week day, and calculating arrays of days for use in calendar displays.