UtilsGetOADateTime Method

Method to convert a date or date and time into the internal Excel time format (OAdate)

Namespace: NanoXLSX
Assembly: NanoXLSX (in NanoXLSX.dll) Version: 2.6.2+7f12a949130e0be1e987e553d2d08c083176cdca

Syntax

public static double GetOADateTime(
	DateTime date,
	bool skipCheck = false
)

date DateTime: Date to process
skipCheck Boolean (Optional): Optional flag to skip the validity check if set to true

Double
Date or date and time as number

Exceptions

Exception	Condition
FormatException	Throws a FormatException if the passed date cannot be translated to the OADate format

Remarks

Excel assumes wrongly that the year 1900 is a leap year. There is a gap of 1.0 between 1900-02-28 and 1900-03-01. This method corrects all dates from the first valid date (1900-01-01) to 1900-03-01. However, Excel displays the minimum valid date as 1900-01-00, although 0 is not a valid description for a day of month. In conformance to the OAdate specifications, the maximum valid date is 9999-12-31 23:59:59 (plus 999 milliseconds).
See also: https://docs.microsoft.com/en-us/dotnet/api/system.datetime.tooadate?view=netcore-3.1
See also: https://docs.microsoft.com/en-us/office/troubleshoot/excel/wrongly-assumes-1900-is-leap-year