Dates and DateTime
Range["A1"].Value = "08/11/04"
This value could be interpreted as any of the following dates depending on the locale of the current thread
August 11, 2004
November 8, 2004
November 4, 2008
The workaround is to never pass dates as literal strings into Excel.
Always construct a date using the System.DateTime object and pass it to Excel using the DateTime.ToOADate method
The ToOADate method converts a DateTime to an OLE Automation date which is the date format used by Excel.
System.DateTime odate = new System.DateTime(2014,4,11);
range1.Value = odate.ToOADate();
Excel calculates the number of days elapsed since 31 December 1899
.NET calculates the number of days elapsed since 1 January 1900
To convert an Excel date in 1900 that is earlier than 1 March 1900 into a DateTime object you must add one day
Excel cannot represent days before 1 January 1900 or (I January 1904) so when converting a DateTime into an Excel date, you have to pass a string rather than a number representing the date.