C# close excel handle after reading xls

Question

I am attempting to open an xls file, read in several rows of data, form a custom list from data and then close the excel sheet. This is what I have:

InitializeWorkbook(Path);
List<Custom> list = new List<Custom>();

Worksheet wkSht = (Worksheet)workBk.Worksheets[3];

if (wkSht.Name.Equals("Sht3", StringComparison.OrdinalIgnoreCase))
{
    Range PartNumRange = wkSht.get_Range("A:A", System.Reflection.Missing.Value);
    Range RevRange = wkSht.get_Range("C:C", System.Reflection.Missing.Value);
    Range SwRange = wkSht.get_Range("L:L", System.Reflection.Missing.Value);
    Range NomenRange = wkSht.get_Range("M:M", System.Reflection.Missing.Value);

    // Start at Row 6
    int i = 6;
    object Num = (PartNumRange[i, 1] as Range).Text;
    object Nomen = (NomenRange[i, 1] as Range).Text;
    object Sw = (SwRange[i, 1] as Range).Text;
    object SwRev = (RevRange[i, 1] as Range).Text;

    while (!string.IsNullOrEmpty(Num.ToString()) || !string.IsNullOrEmpty(Nomen.ToString()) || !string.IsNullOrEmpty(Sw.ToString()) || !string.IsNullOrEmpty(SwRev.ToString()))
    {
        if (!string.IsNullOrEmpty(Nomen.ToString()) && !string.IsNullOrEmpty(Sw.ToString()) && !string.IsNullOrEmpty(SwRev.ToString())
        {
            Custom item = new Custom();

            item.PartNumber = (PartNumRange[i, 1] as Range).Text.ToString();
            item.Nomenclature = (NomenRange[i, 1] as Range).Text.ToString();
            item.SwNumber = (SwRange[i, 1] as Range).Text.ToString();
            item.SwRevision = (RevRange[i, 1] as Range).Text.ToString();

            list.Add(item);
        }

        i++;
        Num = (PartNumRange[i, 1] as Range).Text;
        Nomen = (NomenRange[i, 1] as Range).Text;
        Sw = (SwRange[i, 1] as Range).Text;
        SwRev = (RevRange[i, 1] as Range).Text;
    }

    GC.Collect();
    GC.WaitForPendingFinalizers();

    Marshal.ReleaseComObject(PartNumRange);
    Marshal.ReleaseComObject(RevRange);
    Marshal.ReleaseComObject(SwRange);
    Marshal.ReleaseComObject(NomenRange);

    Marshal.ReleaseComObject(wkSht);
    workBk.Close(false, System.Reflection.Missing.Value, false);
    Marshal.ReleaseComObject(workBk);

    Marshal.ReleaseComObject(ExcelWorkSheets);

    ExcelApp.Quit();
    Marshal.ReleaseComObject(ExcelApp);

    GC.Collect();
    GC.WaitForPendingFinalizers();
}

I dont know why but Excel is not closing after I finish executing. Only when the program exits does Excel exit. I have tried all sorts of combinations and have avoided the two dot rule but still a no go. Any ideas on what I'm missing?

EDIT: Calling ExcelApp.Quit closes both ExcelApp and ExcelWorksheets.

Believe me, I walked the Excel automation way (two dot rule, marshal release and all), then I discovered Flexcel, and I never looked back. You might consider this solution? — Vinzz
– Vinzz, Commented Oct 2, 2012 at 15:49

Community · Accepted Answer · 2017-05-23 10:24:52Z

1

You might want to take a look at this post: How do I properly clean up Excel interop objects?

There's a lot of in-depth discussions about handling COM objects in C# that you might find helpful. Worth a read.

edited May 23, 2017 at 10:24

CommunityBot

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answered Oct 2, 2012 at 16:01

woodykiddy

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2 Comments

Richard Morgan Over a year ago

The question linked above is very good. In fact, an answer there maybe the same problem: workBk.Worksheets[3] is creating a wrapper around the Worksheets COM Object.

dangerisgo Over a year ago

Rich, that was it. There was a few other things I had noticed in the API I was using (that had InitializeWorkbook and CloseExcel methods in it) to control Excel that were also doing the same thing (like ExcelApp.Workbook.Open()) so I had fixed those and everything is working now. Thanks!

Eric J. · Accepted Answer · 2012-10-02 15:49:20Z

0

You also need to call close on

ExcelWorkSheets
ExcelApp

Calling Marshal.ReleaseComObject disposes the runtime callable wrapper, but leaves the application itself still alive and kicking.

answered Oct 2, 2012 at 15:49

Eric J.

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1 Comment

dangerisgo Over a year ago

ExcelApp.Quit closes ExcelApp and ExcelWorkSheets, sorry forgot to mention that.

Aghilas Yakoub · Accepted Answer · 2012-10-02 15:53:25Z

0

You can try with this code - it's work fine

while (Marshal.ReleaseComObject(YourRange) > 0) 
{}

while (Marshal.ReleaseComObject(YourWorkSheet) > 0) 
{}

while (Marshal.ReleaseComObject(YourWorkBook) > 0) 
{}

YourApplication.quit()

while (Marshal.ReleaseComObject(YourApplication) > 0) 
{}

answered Oct 2, 2012 at 15:53

Aghilas Yakoub

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2 Comments

dangerisgo Over a year ago

I just tried this and it Excel is still running. I have updated the OP with an update.

Aghilas Yakoub Over a year ago

@dangerisgo add while to your code in order to clean all instance, i had the same problem, i resolved with while;;;; But you can delete GC.Collect(); GC.WaitForPendingFinalizers();

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