JDDayOfWeek

(PHP 4, PHP 5, PHP 7)

JDDayOfWeek — 返回星期的日期

说明

mixed jddayofweek ( int $julianday [, int $mode = CAL_DOW_DAYNO ] )

返回星期的日期，根据模式不同可能是字符串或是整数。

参数

julianday

一个julian天数。

mode

**历法星期模式**
Mode	Meaning
0 (默认)	返回数字形式(0=Sunday, 1=Monday, etc)
1	返回字符串形式 (English-Gregorian)
2	返回缩写形式的字符串 (English-Gregorian)

返回值

数字或字符串形式的星期数。

User Contributed Notes

kevind at communitycolor dot com 03-Mar-2017 05:24


You need to check to see how your client wants to represent the day of week. This function returns 0 for Sundays. ISO 8601 uses 7 for Sundays.



BTW, You can also calculate the day of week with modular division:



$dow = (1 + $julianday) % 7; // returns 0 for Sundays.

$dow = ($julianday % 7) + 1; // returns 7 for Sundays.



https://en.wikipedia.org/wiki/Julian_day#Finding_day_of_week_given_Julian_day_number



To make matters confusing. The Julian Date starts at noon UTC. Some programs such as SQLITE3 use real numbers to record date and time. If you pass this function a float; it will return a different day of week for the morning than for the afternoon.



When given a julianday with a decimal part you will need to add a half day and may need further adjustment for your timezone.

alex a khimich d org 28-Sep-2015 04:01


In my case i had lots of head pain with returning day number using this function. 

Here is bypass solution using just date():



<?php

$first_day_of_September=date('w', strtotime('1-09-2015')); // 2

?>

nrkkalyan at rediffmail dot com 26-Feb-2005 07:08


You can get todays day time and date using this code





<?php


echo date("d")." "; 


echo date("m")." ";


echo date("Y")." ";


echo date("h:i:s A");





ECHO ' <br/>';


echo jddayofweek ( cal_to_jd(CAL_GREGORIAN, date("m"),date("d"), date("Y")) , 1 );


?>

php at xtramicro dot com 07-Sep-2004 05:28


Be aware that date() and mktime() only work as long as you move within the UNIX era (1970 - 2038 / 0x0 - 0x7FFFFFFF in seconds). Outside that era those functions are only generating errors.





In other words: mktime(0, 0, 0, 12, 31, 1969) *DOES NOT* work (and so doesn't date() fed with with mktime()'s result from above). But cal_to_jd(CAL_GREGORIAN, 12, 11, 1969) *DOES WORK*.





And please note that the calendar-extension's functions arguments follow the US date order: month - day - year.