Problem with closing the C# workbook

[Ram Baran]

Hi,

I am opening a excel file by the C# code and performing some operation and close it. it is working fine.

I am facing problem, when any other excel file is already open, my file open along with that, when i open file through the code.
& doesnt get closed by code, as it happens in normal situation.

If i close it by killing the process, then the file already open is also closed along with that. code is following. Thanks in advance.

System.Data.DataTable objExcelData;
 
            objM_oExcelApp = new Excel.Application();
 
            objExcelData = new System.Data.DataTable("ExcelData");
 
            objM_oBook = objM_oExcelApp.Workbooks.Open(strFilePath, 0, false, 5, "", "", true, Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, null, null);
 
            objM_oSheet = (Excel._Worksheet)objM_oBook.ActiveSheet;
             .......          
             .......
 
            try
            {
                objM_oBook.SaveAs(strFilePath, Missing.Value, Missing.Value, Missing.Value,
                    Missing.Value, Missing.Value, xmlSave, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value);
                objM_oBook.Close(false, false, Missing.Value);
                objM_oExcelApp.Workbooks.Close();
 
                System.Runtime.InteropServices.Marshal.ReleaseComObject
                                    (objM_oBook);
                objM_oBook = null;
 
                blnReturnValue = true;  
            }
            catch
            {
                objM_oBook.Close(false, false, Missing.Value);
                System.Runtime.InteropServices.Marshal.ReleaseComObject
                                    (objM_oBook);
                objM_oBook = null;
                blnReturnValue = false;  
            }
 
            objM_oExcelApp.DisplayAlerts = true; 
 
            Program.KillExcelProcess(objM_oExcelApp); 
-----------------------------------------
 [DllImport("user32.dll")] 
        static extern int GetWindowThreadProcessId(int hWnd, out IntPtr lpdwProcessId);
 
 
public static void KillExcelProcess(Excel.Application exl)
        {
            IntPtr processId = default(IntPtr);
            GetWindowThreadProcessId(exl.Hwnd, out processId); 
            Process excelProcess = Process.GetProcessById(processId.ToInt32()); 
            Debug.WriteLine(processId);
            excelProcess.Kill();
        }
 

[icesign]

Try to release ALL com objects.

objM_oBook = objM_oExcelApp.Workbooks.Open(strFilePath, 0, false, 5, "", "", true, Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, null, null); 

Here "Workbooks" is not just a collection, but a COM object which is created when you access it. You need to release it too with ReleaseComObject.

Maybe this little class will help you.

    public class ComObject<T> : IDisposable
    {
        private T reference;
        private bool disposed;
 
        protected ComObject()
        {
        }
 
        public ComObject(T reference)
        {
            if (reference == null)
                throw new ArgumentNullException("reference");
 
            this.reference = reference;
        }
 
        public T Reference
        {
            get
            {
                if (this.disposed)
                    throw new ObjectDisposedException(this.GetType().Name);
 
                return this.reference;
            }
            protected set
            {
                if (value == null)
                    throw new ArgumentNullException("value");
 
                if (this.reference != null && !this.disposed)
                    this.Dispose(true);
 
                this.reference = value;
 
                this.disposed = false;
            }
        }
 
        public void Dispose()
        {
            this.Dispose(true);
 
            GC.SuppressFinalize(this);
        }
 
        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (this.reference != null)
                    Marshal.ReleaseComObject(this.reference);
 
                this.reference = default(T);
 
                this.disposed = true;
            }
        }
 
        ~ComObject()
        {
            this.Dispose(false);
        }
    }
 

            using (ComObject<Excel.IWorkbooks> workbooks = new ComObject<Excel.IWorkbooks>(objM_oExcelApp.Workbooks))
            {
                //use it through workbooks.Reference
            }
 

[Ram Baran]

Thanks for precious help.