PHP Calendar Introduction
The calendar functions are useful when working with different calendar formats. The standard it is based on is the Julian day count (Julian day count is a count of days starting from January 1, 4713 B.C.). Note that the Julian day count is not the same as the Julian calendar!
Note: To convert between calendar formats, you must first convert to Julian day count, then to the calendar format.
Installation
The windows version of PHP has built-in support for the calendar extension. So, the calendar functions will work automatically.
However, if you are running the Linux version of PHP, you will have to compile PHP with –enable-calendar to get the calendar functions to work.
PHP Calendar Functions
PHP: indicates the earliest version of PHP that supports the function.
| Function | Description | PHP |
| cal_days_in_month() | Returns the number of days in a month for a specified year and calendar | 4 |
| cal_from_jd() | Converts a Julian day count into a date of a specified calendar | 4 |
| cal_info() | Returns information about a given calendar | 4 |
| cal_to_jd() | Converts a date to Julian day count | 4 |
| easter_date() | Returns the Unix timestamp for midnight on Easter of a specified year | 3 |
| easter_days() | Returns the number of days after March 21, on which Easter falls for a specified year | 3 |
| FrenchToJD() | Converts a French Republican date to a Julian day count | 3 |
| GregorianToJD() | Converts a Gregorian date to a Julian day count | 3 |
| JDDayOfWeek() | Returns the day of a week | 3 |
| JDMonthName() | Returns a month name | 3 |
| JDToFrench() | Converts a Julian day count to a French Republican date | 3 |
| JDToGregorian() | Converts a Julian day count to a Gregorian date | 3 |
| jdtojewish() | Converts a Julian day count to a Jewish date | 3 |
| JDToJulian() | Converts a Julian day count to a Julian date | 3 |
| jdtounix() | Converts a Julian day count to a Unix timestamp | 4 |
| JewishToJD() | Converts a Jewish date to a Julian day count | 3 |
| JulianToJD() | Converts a Julian date to a Julian day count | 3 |
| unixtojd() | Converts a Unix timestamp to a Julian day count | 4 |
PHP Calendar Constants
PHP: indicates the earliest version of PHP that supports the constant.
| Constant | Description | PHP |
| CAL_GREGORIAN | Gregorian calendar | 3 |
| CAL_JULIAN | Julian calendar | 3 |
| CAL_JEWISH | Jewish calendar | 3 |
| CAL_FRENCH | French Republican calendar | 3 |
| CAL_NUM_CALS | 3 | |
| CAL_DOW_DAYNO | 3 | |
| CAL_DOW_SHORT | 3 | |
| CAL_DOW_LONG | 3 | |
| CAL_MONTH_GREGORIAN_SHORT | 3 | |
| CAL_MONTH_GREGORIAN_LONG | 3 | |
| CAL_MONTH_JULIAN_SHORT | 3 | |
| CAL_MONTH_JULIAN_LONG | 3 | |
| CAL_MONTH_JEWISH | 3 | |
| CAL_MONTH_FRENCH | 3 | |
| CAL_EASTER_DEFAULT | 4 | |
| CAL_EASTER_DEFAULT | 4 | |
| CAL_EASTER_ROMAN | 4 | |
| CAL_EASTER_ALWAYS_GREGORIAN | 4 | |
| CAL_EASTER_ALWAYS_JULIAN | 4 | |
| CAL_JEWISH_ADD_ALAFIM_GERESH | 5 | |
| CAL_JEWISH_ADD_ALAFIM | 5 | |
| CAL_JEWISH_ADD_GERESHAYIM |