How to make correct date format when writing data to Excel
This worked for me:
sheet.Cells[currentRow, ++currentColumn] = "'" + theDate.ToString("MM/dd/yy");
Note the tick mark added before the date.
Did you try formatting the entire column as a date column? Something like this:
Range rg = (Excel.Range)worksheetobject.Cells[1,1];
rg.EntireColumn.NumberFormat = "MM/DD/YYYY";
The other thing you could try would be putting a single tick before the string expression before loading the text into the Excel cell (not sure if that matters or not, but it works when typing text directly into a cell).
Try using
DateTime.ToOADate()
And putting that as a double in the cell. There could be issues with Excel on Mac Systems (it uses a different datetime-->double conversion), but it should work well for most cases.
Hope this helps.