C# - How to add an Excel Worksheet programmatically - Office XP / 2003

Question

I am just starting to fiddle with Excel via C# to be able to automate the creation, and addition to an Excel file.

I can open the file and update its data and move through the existing worksheets. My problem is how can I add new sheets?

I tried:

Excel.Worksheet newWorksheet;
newWorksheet = (Excel.Worksheet)excelApp.ThisWorkbook.Worksheets.Add(
                Type.Missing, Type.Missing, Type.Missing, Type.Missing);

But I get below COM Exception and my googling has not given me any answer.

Exception from HRESULT: 0x800A03EC Source is: "Interop.Excel"

I am hoping someone maybe able to put me out of my misery.

Answer 1

You need to add a COM reference in your project to the "Microsoft Excel 11.0 Object Library" - or whatever version is appropriate.

This code works for me:

private void AddWorksheetToExcelWorkbook(string fullFilename,string worksheetName)
{
    Microsoft.Office.Interop.Excel.Application xlApp = null;
    Workbook xlWorkbook = null;
    Sheets xlSheets = null;
    Worksheet xlNewSheet = null;

    try {
        xlApp = new Microsoft.Office.Interop.Excel.Application();

        if (xlApp == null)
            return;

        // Uncomment the line below if you want to see what's happening in Excel
        // xlApp.Visible = true;

        xlWorkbook = xlApp.Workbooks.Open(fullFilename, 0, false, 5, "", "",
                false, XlPlatform.xlWindows, "",
                true, false, 0, true, false, false);

        xlSheets = xlWorkbook.Sheets as Sheets;

        // The first argument below inserts the new worksheet as the first one
        xlNewSheet = (Worksheet)xlSheets.Add(xlSheets[1], Type.Missing, Type.Missing, Type.Missing);
        xlNewSheet.Name = worksheetName;

        xlWorkbook.Save();
        xlWorkbook.Close(Type.Missing,Type.Missing,Type.Missing);
        xlApp.Quit();
    }
    finally {
        Marshal.ReleaseComObject(xlNewSheet);
        Marshal.ReleaseComObject(xlSheets);
        Marshal.ReleaseComObject(xlWorkbook);
        Marshal.ReleaseComObject(xlApp);
        xlApp = null;
    }
}

Note that you want to be very careful about properly cleaning up and releasing your COM object references. Included in that StackOverflow question is a useful rule of thumb: "Never use 2 dots with COM objects". In your code; you're going to have real trouble with that. My demo code above does NOT properly clean up the Excel app, but it's a start!

Some other links that I found useful when looking into this question:

• Opening and Navigating Excel with C#
• How to: Use COM Interop to Create an Excel Spreadsheet (C# Programming Guide)
• How to: Add New Worksheets to Workbooks

According to MSDN

To use COM interop, you must have administrator or Power User security permissions.

Hope that helps.