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VIII. Calendar Functions
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.boogle.com/info/cal-overview.html. Excerpts from this page are
included in these instructions, and are in quotes.
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. This extension has no configuration directives defined in php.ini. This extension has no resource types defined.
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.
The following constants are available since PHP 4.3.0 :
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
User Contributed Notes
Calendar Functions
pouya
03-Apr-2004 01:39
There is an implementation of the Persian calendar at www.farsiweb.info.
jthome at fcgov dot com
02-Oct-2003 02:38
Had a similar problem as curlee, except I needed to create a JDE_ERP date. [format is CYYDDD]
<?php
function jde_date_create($month, $day, $year){
$jde_year_prefix = substr($year, 0, 1) - 1;
$jde_year_suffix = substr($year, -2);
$timestamp = mktime(0,0,0,$month, $day, $year);
$baseline_timestamp = mktime(0,0,0,1,0,$year);
$day_count = round(($timestamp - $baseline_timestamp)/86400);
$day_count_padded = str_pad($day_count,3,"0",STR_PAD_LEFT);
return ($jde_year_prefix . $jde_year_suffix . $day_count_padded);
}
echo jde_date_create(6,25,2000);?>
--
Jim
curlee at mindspring dot com
29-Aug-2003 11:55
I solved a problem with Julian dates that are used in the JD Edwards ERP package (running on AS/400). The Julian format for this system is as follows: CYYDDD
Where C is 0 for 1900 and 1 for 2000
DDD is the day of the year count
I used the mktime built-in php function to convert dates to the normal DD/MM/YYYY format. This function will convert dates that are between 1970 and 2038 (limitation of unix timestamps and the mktime function)
The $jde_date var needs to be a 6 len STRING.... if you use a numeric var type it will drop the leading 0 for any date that represents 1900.... this will botch the substr functions and thus make the whole thing wrong.
function jde_date_conv($jde_date)
{
$ct = substr($jde_date,0,1);
$yr = substr($jde_date,1,2);
$dy = substr($jde_date,3,3);
if($ct == 0) $yr_pfx = 19;
if($ct == 1) $yr_pfx = 20;
$tlt_yr = $yr_pfx.$yr;
$base_time = mktime(0,0,0,1,0,$tlt_yr);
$unix_time = ($dy * 86400) + $base_time;
return date("m/d/Y" , $unix_time);
}
carlj at vibez dot ca
17-Jun-2003 03:28
Why not do something like this, to find the number of days in a month?
$monthNum = date("n"); // or any value from 1-12
$year = date("Y"); // or any value >= 1
$numDays = date("t",mktime(0,0,0,$monthNum,1,$year))
This will tell you if there is 28-31 days in a month
dy64 at dy64 dot de
12-Nov-2002 09:18
Best performance:
/*
* Find the number of days in a month
* Year is between 1 and 32767 inclusive
* Month is between 1 and 12 inclusive
*/
function DayInMonth($month, $year) {
var $daysInMonth = array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
if ($month != 2) return $daysInMonth[$month - 1];
return (checkdate($month, 29, $year)) ? 29 : 28;
}
kmcm at bigfoot dot com
20-Jan-2002 09:42
if, like me, you don't have a PHP build that includes the cal functions, you may want to use this function for sorting out leap year.
function days_in_feb($year){
//$year must be YYYY
//[gregorian] leap year math :
if ($year < 0) $year++;
$year += 4800;
if ( ($year % 4) == 0) {
if (($year % 100) == 0) {
if (($year % 400) == 0) {
return(29);
} else {
return(28);
}
} else {
return(29);
}
} else {
return(28);
}
}
of course the next leap year isn't until the end of the century but this makes for timeless code I guess ...or if you are using 2000 in your dates or are going far back in time, etc, it is necessary.
mikebabcock at pobox dot com
17-Jul-2000 12:20
There are two world calculations for the date of Easter. The Easter date function should account for this; one used (generally) by the Western world and one (generally) used by the Eastern (the official date used by the East Orthodox Church).
ssharma at odc dot net
31-Jan-2000 06:36
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