jddayofweek

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

jddayofweek — 返回星期几

说明

jddayofweek(int $julian_day, int $mode = CAL_DOW_DAYNO): int|string

返回星期几，根据模式不同返回 string 或 int。

参数

julian_day

int 类型的儒略日数

mode

**历法星期模式**
模式	含义
0 (默认)	返回 int 类型的星期几（0 = Sunday， 1 = Monday，等等）
1	以英文返回公历形式的 string 类型的星期几
2	以英文返回公历形式的 string 类型的星期几缩写

返回值

int 或 string 类型的公历星期几。

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kevind at communitycolor dot com ¶

7 years ago

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.