Set format for all cells in Excel without selections, using C# and VSTO

Question

Let's assume that I want to set the format ("Text", "Number", "Percent", "Date", and so on) for all cells in the Excel worksheet.

I now how to set the format for a single row or a single column. For example, the code setting the "Percent" format for all cells of the 3rd row looks as follows (the decimal delimiter depends on your Windows localization):

this.worksheet.Rows[3].NumberFormat = "%0,00";

However, when I'm trying to do the same for all cells of the worksheet with the following code:

this.worksheet.Cells.NumberFormat = "%0,00";

, I get a problem - in fact, the format of the cells will be changed but to a some wrong format (in the present case, the real set format will be "#000%", which is recognized by Excel as a "Custom Format").

I know how to solve this problem using selections. So, the following code performs the mentioned task perfectly:

this.worksheet.Cells.Select();
this.worksheet.Application.Selection.NumberFormat = "%0,00";

, however, I really want to solve this problem without selections. How can I do it?

Answer 1

Although I find your responses to people trying to help you very offensive I tried to ignore that a bit to keep in mind that we try to help each other here and focus on finding a solution for the scenario.

So here is my final attempt to please you ...

[TestMethod]
public void TestExcelNumberFormatOnWholeSheet()
{
    Excel.Application excel = new Excel.Application();
    excel.Visible = true;

    Excel.Workbook workbook1 = excel.Workbooks.Add();
    Excel.Worksheet sheet = workbook1.Sheets.Add();

    var lastCol = sheet.Range["a1"].End[Excel.XlDirection.xlToRight].Column;
    var lastRow = sheet.Cells[65536, lastCol].End[Excel.XlDirection.xlDown].Row;

    sheet.Range["a1", sheet.Cells[lastRow, lastCol]].NumberFormat = "%0,00";
}

I've tested it here and seems to work (keep in mind that as you already mentioned you may need to switch the decimal character depending on your localization).

Answer 2

Let me answer my own question.

If shortly, instead of the code

this.worksheet.Cells.NumberFormat = "%0,00";

, one should use the following one:

((dynamic)this.worksheet.Cells).NumberFormat = "%0,00";

Then, the result format will be correct!

Now, my explanation of this: The NumberFormat property looks to be correctly applicable only for the dynamic type, but not for the Microsoft.Office.Interop.Excel.Range type. When one writes something like this.worksheet.Cells or this.worksheet.Range["A1", "C3"] , he/she gets the Microsoft.Office.Interop.Excel.Range type; when one writes something like this.worksheet.Rows[3] , he/she gets the dynamic type. Therefore, in order to use the NumberFormat property, just cast your Microsoft.Office.Interop.Excel.Range object to the dynamic one!