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jddayofweek

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

jddayofweek — 曜日を返す

説明

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

曜日を返します。モードに依存した文字あるいは整数を返す事が出来ます。

パラメータ

julian_day

ユリウス積算日を表す整数値。

mode

**暦の曜日モード**
モード	意味
0 (デフォルト)	整数で曜日番号 (0=Sunday, 1=Monday, 等)を返します。
1	曜日(英グレゴリウス)を含む文字列を返します。
2	曜日の省略形(英グレゴリウス)を含む文字列を返します。

戻り値

グレゴリウス暦の曜日を表す数値あるいは文字列を返します。

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User Contributed Notes 2 notes

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phimuskapsi at gmail dot com ¶

4 years ago


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.

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-1

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.

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