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.
jddayofweek
(PHP 4, PHP 5, PHP 7, PHP 8)
jddayofweek — Returns the day of the week
Description
Returns the day of the week. Can return a string or an integer depending on the mode.
Parameters
-
julian_day -
A julian day number as integer
-
mode -
Calendar week modes Mode Meaning 0 (Default) Return the day number as an int (0=Sunday, 1=Monday, etc) 1 Returns string containing the day of week (English-Gregorian) 2 Return a string containing the abbreviated day of week (English-Gregorian)
Return Values
The gregorian weekday as either an integer or string.
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User Contributed Notes 2 notes
phimuskapsi at gmail dot com ¶
4 years ago
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.
