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    public class ExcelMethods
    {
         private static Excel.Application xlApp;
         private static Excel.Workbook xlWb;
         private static Excel.Worksheet xlWs;
         private static object misValue = Missing.Value;
        
        public static void OpenExcelFile(string file)
        {
            xlApp = new Excel.Application();
            xlWb =  xlApp.Workbooks.Open(file, 0, true, 5, "", "", true, Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
            xlWs = (Excel.Worksheet)xlWb.Worksheets[1];
        }

        public static void WriteDataToExcelFile(string data, long row, long column)
        {
            xlWs.Cells[row, column] = data;
        }

        public static void ShowExcelFile(bool show)
        {
            xlApp.Visible = show;
        }

        public static void CloseExcelFile()
        {
            xlWb.Close(true, misValue, misValue);
            xlApp.Quit();

            releaseObject(xlWs);
            releaseObject(xlWb);
            releaseObject(xlApp);
        }

        private static void releaseObject(object obj)
        {
            try
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
                obj = null;
            }
            catch (Exception)
            {
                obj = null;
            }
            finally
            {
                GC.Collect();
            }
        } 
    }                    

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        public static void SaveExcelFile(string path)
        {
            xlWb.ExportAsFixedFormat(Excel.XlFixedFormatType.xlTypePDF, path, misValue, misValue, misValue, misValue, misValue, misValue, misValue);
        }