JDDayOfWeek

(PHP 4, PHP 5, PHP 7, PHP 8)

JDDayOfWeek返回星期的日期

说明

jddayofweek ( int $julianday , int $mode = CAL_DOW_DAYNO ) : mixed

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

phimuskapsi at gmail dot com 24-Aug-2020 07:16
When using mode 1 or 2, the number returned will NOT match mode 0.

jddayofweek(0, 1) = 'Monday' not 'Sunday' as expected.

This can cause discordance between the UI and the value saved.
kevind at communitycolor dot com 03-Mar-2017 08:24
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.
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