DAYS
Calculates the difference between two date values. Returns the number of days between the two days. May return a fraction of a day when the arguments include time parts.
This function is part of the Open Document Format for Office Applications (OpenDocument) standard Version 1.2. (ISO/IEC 26300:2-2015)
DAYS(Date2; Date1)
Date1 是指開始日期，Date2 為指結束日期。若 Date2 是早於 Date1 的日期，則結果會是負數。
When entering dates as part of formulas, slashes or dashes used as date separators are interpreted as arithmetic operators. Therefore, dates entered in this format are not recognized as dates and result in erroneous calculations. To keep dates from being interpreted as parts of formulas use the DATE function, for example, DATE(1954;7;20), or place the date in quotation marks and use the ISO 8601 notation, for example, "1954-07-20". Avoid using locale dependent date formats such as "07/20/54", the calculation may produce errors if the document is loaded under different locale settings.
Unambiguous conversion is possible for ISO 8601 dates and times in their extended formats with separators. If a #VALUE! error occurs, then unselect Generate #VALUE! error in LibreOffice - PreferencesTools - Options - LibreOffice Calc - Formula, button Details... in section "Detailed Calculation Settings", Conversion from text to number list box.
=DAYS(TODAY();"2010-01-01")) returns the number of days from January 1, 2010 until today.
=DAYS("1990-10-10";"1980-10-10") returns 3652 days.
=DAYS(NOW(); TODAY()) returns a fraction of the current day.