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jddayofweek

(PHP 4, PHP 5, PHP 7)

jddayofweek曜日を返す

説明

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

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

julianday

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。

返り値

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
1 month 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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0
kevind at communitycolor dot com
3 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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