PHP Functions Essential Reference

Chapter 4. Calendar Functions

The calendar functions focus on converting dates between calendar systems and getting information about dates. The conversion functions either convert a date from a specific calendar system to a Julian day count or convert a Julian day count to a date for a specific calendar system. Julian day counts are a calendar system first introduced in the 16th century for use in astronomical calculations. A Julian day count is the number of days that have passed since noon on January 1, 4713 B.C. (according to the Julian calendar). The sequential, non-repeating nature of Julian days makes them ideal for calculating intervals between events and for acting as a kind of lingua franca for converting between calendar systems. ...