convert excel date to datetime c#

Excel stores the datetime value as a serial number.
The date January 1, 1900 is treated as day 1 and all the date and time
values are calculated accordingly. Also excel saves the time
value as a fractional number from 0 to 1. So the date part
is a whole number and time is the fractional part.

When we use the Range.Value2 method to extract a date time value from excel,
it will return a double value. So we will be using [DateTime.FromOADate] function to get the date value.

Lets say we have a datetime field on the row 1 and col 1 of excel .
Following code will get the datetime value.

DateTime dateValue = DateTime.FromOADate(Convert.ToDouble((ws.Cells[1, 1] as Excel.Range).Value2));

// where ws is the Worksheet.