Calendar Polyfill

A PHP polyfill for the calendar extension.

This library provides a pure PHP implementation of all calendar extension functions, allowing you to use calendar functionality without requiring the calendar extension to be installed.

Requirements

• PHP 8.0 or higher

Installation

composer require roukmoute/polyfill-calendar

Supported Calendars

Constant	Calendar
CAL_GREGORIAN	Gregorian Calendar
CAL_JULIAN	Julian Calendar
CAL_JEWISH	Jewish Calendar
CAL_FRENCH	French Republican Calendar

Available Functions

Calendar Conversion

Function	Description
cal_to_jd	Converts from a supported calendar to Julian Day Count
cal_from_jd	Converts from Julian Day Count to a supported calendar
cal_days_in_month	Return the number of days in a month for a given year and calendar
cal_info	Returns information about a particular calendar

Gregorian Calendar

Function	Description
gregoriantojd	Converts a Gregorian date to Julian Day Count
jdtogregorian	Converts Julian Day Count to Gregorian date

Julian Calendar

Function	Description
juliantojd	Converts a Julian Calendar date to Julian Day Count
jdtojulian	Converts a Julian Day Count to Julian Calendar Date

Jewish Calendar

Function	Description
jewishtojd	Converts a date in the Jewish Calendar to Julian Day Count
jdtojewish	Converts a Julian Day Count to the Jewish Calendar

French Republican Calendar

Function	Description
frenchtojd	Converts a date from the French Republican Calendar to a Julian Day Count
jdtofrench	Converts a Julian Day Count to French Republican Calendar Date

Easter Functions

Function	Description
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

Unix Timestamp Conversion

Function	Description
unixtojd	Convert Unix timestamp to Julian Day
jdtounix	Convert Julian Day to Unix timestamp

Utility Functions

Function	Description
jddayofweek	Returns the day of the week for a Julian Day
jdmonthname	Returns a month name

Usage Examples

Converting between calendars

// Gregorian to Julian Day Count
$jd = gregoriantojd(12, 25, 2024); // December 25, 2024

// Julian Day Count to Gregorian
$date = jdtogregorian($jd); // "12/25/2024"

// Convert to Jewish calendar
$jewish = jdtojewish($jd); // "10/23/5785"

Getting Easter date

// Get Easter Sunday timestamp for 2025
$easter = easter_date(2025);
echo date('Y-m-d', $easter); // 2025-04-20

// Get days after March 21
$days = easter_days(2025); // 30

Calendar information

// Get info about all calendars
$info = cal_info();

// Get info about a specific calendar
$gregorian = cal_info(CAL_GREGORIAN);
print_r($gregorian['months']); // Array of month names

Days in a month

// February 2024 (leap year)
$days = cal_days_in_month(CAL_GREGORIAN, 2, 2024); // 29

// February 2023 (not a leap year)
$days = cal_days_in_month(CAL_GREGORIAN, 2, 2023); // 28

Available Constants

Calendar Types

• CAL_GREGORIAN, CAL_JULIAN, CAL_JEWISH, CAL_FRENCH, CAL_NUM_CALS

Day of Week Modes

• CAL_DOW_DAYNO, CAL_DOW_SHORT, CAL_DOW_LONG

Month Name Modes

• CAL_MONTH_GREGORIAN_SHORT, CAL_MONTH_GREGORIAN_LONG
• CAL_MONTH_JULIAN_SHORT, CAL_MONTH_JULIAN_LONG
• CAL_MONTH_JEWISH, CAL_MONTH_FRENCH

Easter Calculation Modes

• CAL_EASTER_DEFAULT, CAL_EASTER_ROMAN
• CAL_EASTER_ALWAYS_GREGORIAN, CAL_EASTER_ALWAYS_JULIAN

Jewish Calendar Formatting

• CAL_JEWISH_ADD_ALAFIM_GERESH, CAL_JEWISH_ADD_ALAFIM, CAL_JEWISH_ADD_GERESHAYIM

License

This library is released under the MIT license.