cal_to_jd

Converts from a supported calendar to Julian Day Count (PHP 4 >= 4.1.0, PHP 5)
int cal_to_jd ( int calendar, int month, int day, int year )

cal_to_jd() calculates the Julian day count for a date in the specified calendar. Supported calendars are CAL_GREGORIAN, CAL_JULIAN, CAL_JEWISH and CAL_FRENCH.

See also cal_from_jd().