X. Calendar Functions

Introduction

The calendar extension presents a series of functions to simplify converting between different calendar formats. The intermediary or standard it is based on is the Julian Day Count. The Julian Day Count is a count of days starting from January 1st, 4713 B.C. To convert between calendar systems, you must first convert to Julian Day Count, then to the calendar system of your choice. Julian Day Count is very different from the Julian Calendar! For more information on Julian Day Count, visit http://www.hermetic.ch/cal_stud/jdn.htm. For more information on calendar systems visit http://www.fourmilab.ch/documents/calendar/. Excerpts from this page are included in these instructions, and are in quotes.

Installation

To get these functions to work, you have to compile PHP with --enable-calendar.

The windows version of PHP has built in support for this extension. You do not need to load any additional extension in order to use these functions.

Runtime Configuration

This extension has no configuration directives defined in php.ini.

Resource Types

This extension has no resource types defined.

Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

CAL_GREGORIAN (integer)
CAL_JULIAN (integer)
CAL_JEWISH (integer)
CAL_FRENCH (integer)
CAL_NUM_CALS (integer)
CAL_DOW_DAYNO (integer)
CAL_DOW_SHORT (integer)
CAL_DOW_LONG (integer)
CAL_MONTH_GREGORIAN_SHORT (integer)
CAL_MONTH_GREGORIAN_LONG (integer)
CAL_MONTH_JULIAN_SHORT (integer)
CAL_MONTH_JULIAN_LONG (integer)
CAL_MONTH_JEWISH (integer)
CAL_MONTH_FRENCH (integer)

The following constants are available since PHP 4.3.0 :

CAL_EASTER_DEFAULT (integer)
CAL_EASTER_ROMAN (integer)
CAL_EASTER_ALWAYS_GREGORIAN (integer)
CAL_EASTER_ALWAYS_JULIAN (integer)

The following constants are available since PHP 5.0.0 :

CAL_JEWISH_ADD_ALAFIM_GERESH (integer)
CAL_JEWISH_ADD_ALAFIM (integer)
CAL_JEWISH_ADD_GERESHAYIM (integer)

Table of Contents
cal_days_in_month -- Return the number of days in a month for a given year and calendar
cal_from_jd -- Converts from Julian Day Count to a supported calendar
cal_info -- Returns information about a particular calendar
cal_to_jd -- Converts from a supported calendar to Julian Day Count
easter_date -- Get Unix timestamp for midnight on Easter of a given year
easter_days -- Get number of days after March 21 on which Easter falls for a given year
FrenchToJD -- Converts a date from the French Republican Calendar to a Julian Day Count
GregorianToJD -- Converts a Gregorian date to Julian Day Count
JDDayOfWeek -- Returns the day of the week
JDMonthName -- Returns a month name
JDToFrench -- Converts a Julian Day Count to the French Republican Calendar
JDToGregorian -- Converts Julian Day Count to Gregorian date
jdtojewish -- Converts a Julian day count to a Jewish calendar date
JDToJulian -- Converts a Julian Day Count to a Julian Calendar Date
jdtounix -- Convert Julian Day to Unix timestamp
JewishToJD -- Converts a date in the Jewish Calendar to Julian Day Count
JulianToJD -- Converts a Julian Calendar date to Julian Day Count
unixtojd -- Convert Unix timestamp to Julian Day