Core PHP Programming, Third Edition

14.2. Alternative Calendars

PHP offers a powerful way to convert dates from one calendar system to another. In order to do this, you must first convert a date into a Julian Day Count. You then convert that integer back into a date according to another calendar.

These functions require the calendar extension. You may load it dynamically, or compile it into PHP.

integer cal_days_in_month(integer calendar, integer month, integer year)

The cal_days_in_month function (Listing 14.13) returns the number of days in a month for a given calendar's month and year. Use one of the constants in Table 14.6 to specify the calendar.

Table 14.6. Calendar Type Constants

Constant	Description
CAL_FRENCH	French Republican Calendar
CAL_GREGORIAN	Gregorian Calendar
CAL_JEWISH ...