easter_date()

(PHP 4, PHP 5, PHP 7)

得到指定年份的复活节午夜时的Unix时间戳。

说明

返回指定年份的复活节午夜时的Unix时间戳。

如果给定的年份超出Unix时间戳的范围（比如1970年以前或2037年以后），该函数将返回一个警告。

复活节的日期是由尼西亚议会在AD325年确定的为每年春分月圆后的第一个星期日。春分一般是在3月21日，这就简化为只要计算满月的日期和紧挨的星期日的日期。这里所用的算法是在532年由Dionysius Exiguus所介绍的，参考了Julian历法和Gregorian历法这两个历法来提高精确度。（在1753年以前用Julian历法计算，该历法是一个以19年为周期来确定月亮的相位的历法。在1753年以后用Gregorian历法计算，该历法由Clavius和Lilius发明，由Pope Gregory 8世在1582年推广）

参数

1970年至2037年之间的数字形式的年份。

返回值

复活节日期的Unix时间戳。

更新日志

范例

easter_date() example

参见

• easter_days()得到指定年份的3月21日到复活节之间的天数 for calculating Easter before 1970 or after 2037

To compute the correct Easter date for Eastern Orthodox Churches I made a function based on the Meeus Julian algorithm: 

I recently had to write a function that allows me to know if today is a holiday.
And in France, we have some holidays which depends on the easter date. Maybe this will be helpful to someone.
Just modify in the $holidays array the actual holidays dates of your country. 

Hey, recently I needed a function to get realization dates in online shop, so here it is (ready to go for polish users, please adjust your dates for any other country): 

I found a problem with holidays timestamp computation and daylight saving time.
An article about it at http://goo.gl/76t31 (in french only, sorry).
In summary, this year (2013) easter begins before adding an hour for daylight saving time (occured sunday at 3:00). It means that if you do $easter + X, where x is a number of seconds equivalent to one day, 39 days or 50 days, the result is not equals to a midnight timestamp...
Here a function to check if a midnight timestamp is equals to an holiday :
function isHoliday( $ts ) {
// Licence : Creative Commons (BY)
// By Webpulser - http://goo.gl/76t31
 $fixed_holidays = array( ’01-01′, ’01-05′, ’08-05′, ’14-07′, ’15-08′, ’11-11′, ’25-12′ );
 $format = ‘d-m’;
 $dm = date($format, $ts);
 if ( in_array($dm, $fixed_holidays) ) return true;
 $easter = easter_date( date(‘Y’, $ts) );
 if ( date($format, $easter +  86400) == $dm ) return true;
 if ( date($format, $easter + 3369600) == $dm ) return true;
 if ( date($format, $easter + 4320000) == $dm ) return true;
 return false;
}
feel free to use / modify.

Thank you, @Maxie, for algorythm for computing Orthodox Easter date.
It can be improved though. You added 13 days in order to map Julian calendar to Gregorian. But 13 days is not a constant. It's an accumulated error fixed in Gregorian and should be calculated with this formula: (int)($year / 100) - (int)($year / 400) - 2

The algorithm from Bigtree is correct if you add some (int) cast