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gaute/convert-ms-date.el

Last active August 29, 2015 14:15
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Convert Microsoft (Excel) timestamp to ISO
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convert-ms-date.el
(defun microsoft-date-to-iso (microsoft-date)
(format-time-string "%Y-%m-%d %H:%M:%S%z" (days-to-time (- (string-to-number microsoft-date) 25569))))
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gaute commented Feb 17, 2015

Microsoft timestamp: 39962.5493055556

39962 is the number of days since December 30, 1899. The fraction part is the elapsed fraction of the day. (0.5 means 12:00, 0.75 means 18:00, etc.)

Emacs' days_to_time converts the number of days since January 1, 1970, including the fraction part.

To convert, we subtract 25569, which is the number of days between 1970-01-01 and 1899-12-30. The fraction part is left alone.

Returned ISO time: 2009-05-29 15:11:00+0200

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