How can I dispose my Excel Application

Question

My code is as follows

Excel.Application xlApp = new Excel.Application();
Excel.Workbook xlWorkbook = xlApp.Workbooks.Open(file);

Excel.Worksheet xlSheet = xlWorkbook.Sheets[1]; // get first sheet
Excel.Range xlRange = xlSheet.UsedRange;

These are the only variables used in my function

foreach (Excel.Worksheet XLws in xlWorkbook.Worksheets)
{
    // do some stuff 

    xlApp.UserControl = false;

    if (xlRange != null)
        System.Runtime.InteropServices.Marshal.FinalReleaseComObject(xlRange);

    if (xlSheet != null)
        System.Runtime.InteropServices.Marshal.FinalReleaseComObject(xlSheet);

    if (xlWorkbook != null)
        System.Runtime.InteropServices.Marshal.FinalReleaseComObject(xlWorkbook);

    xlRange = null;
    xlSheet = null;
    xlWorkbook = null;
    xlApp.Quit();

    System.Runtime.InteropServices.Marshal.FinalReleaseComObject(xlApp);
}

But still I get EXCEL.EXE in Task Manager

Please help?

Solution 1

Kill the excel process which has empty value for MainWindowTitle. Below is an example source code.

    Microsoft.Office.Interop.Excel.Application oXL;
    Microsoft.Office.Interop.Excel._Workbook oWB;
    Microsoft.Office.Interop.Excel._Worksheet oSheet;
    Microsoft.Office.Interop.Excel.Range oRng;
    object misvalue = System.Reflection.Missing.Value;
    try
    {
        //Start Excel and get Application object.
        oXL = new Microsoft.Office.Interop.Excel.Application();
        oXL.Visible = true;

        //Get a new workbook.
        oWB = (Microsoft.Office.Interop.Excel._Workbook)(oXL.Workbooks.Add(""));
        oSheet = (Microsoft.Office.Interop.Excel._Worksheet)oWB.ActiveSheet;

        //Add table headers going cell by cell.
        oSheet.Cells[1, 1] = "First Name";
        oSheet.Cells[1, 2] = "Last Name";
        oSheet.Cells[1, 3] = "Full Name";
        oSheet.Cells[1, 4] = "Salary";

        //Format A1:D1 as bold, vertical alignment = center.
        oSheet.get_Range("A1", "D1").Font.Bold = true;
        oSheet.get_Range("A1", "D1").VerticalAlignment =
            Microsoft.Office.Interop.Excel.XlVAlign.xlVAlignCenter;

        // Create an array to multiple values at once.
        string[,] saNames = new string[5, 2];

        saNames[0, 0] = "John";
        saNames[0, 1] = "Smith";
        saNames[1, 0] = "Tom";

        saNames[4, 1] = "Johnson";

        //Fill A2:B6 with an array of values (First and Last Names).
        oSheet.get_Range("A2", "B6").Value2 = saNames;

        //Fill C2:C6 with a relative formula (=A2 & " " & B2).
        oRng = oSheet.get_Range("C2", "C6");
        oRng.Formula = "=A2 & \" \" & B2";

        //Fill D2:D6 with a formula(=RAND()*100000) and apply format.
        oRng = oSheet.get_Range("D2", "D6");
        oRng.Formula = "=RAND()*100000";
        oRng.NumberFormat = "$0.00";

        //AutoFit columns A:D.
        oRng = oSheet.get_Range("A1", "D1");
        oRng.EntireColumn.AutoFit();

        oXL.Visible = false;
        oXL.UserControl = false;
        oWB.SaveAs("c:\\test505.xls", Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookDefault, Type.Missing, Type.Missing,
                false, false, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange,
                Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);

        oWB.Close(null, null, null);
        oXL.Quit();  //MainWindowTitle will become empty afer being close

        System.Runtime.InteropServices.Marshal.FinalReleaseComObject(oXL);
        System.Runtime.InteropServices.Marshal.FinalReleaseComObject(oWB);

        Process[] excelProcesses = Process.GetProcessesByName("excel");
        foreach (Process p in excelProcesses)
        {
            if (string.IsNullOrEmpty(p.MainWindowTitle)) // use MainWindowTitle to distinguish this excel process with other excel processes 
            {
                p.Kill();
            }
        }
    }
    catch (Exception ex2)
    {

    }

Solution 2

You've got an implicit object left open. Try this

Excel.Application xlApp = new Excel.Application();
Excel.Workbooks xlWorkbooks = xlApp.Workbooks;
Excel.Workbook xlWorkbook = xlWorkbooks.Open(file);
....    

System.Runtime.InteropServices.Marshal.FinalReleaseComObject(xlApp);
System.Runtime.InteropServices.Marshal.FinalReleaseComObject(xlWorkbooks);
System.Runtime.InteropServices.Marshal.FinalReleaseComObject(xlWorkbook);
....