private void button1_Click(object sender, System.EventArgs e)
 {
 StartExcelAndSinkEvents();
 } 

using System.Reflection;
 using System.Diagnostics;
 using Excel = Microsoft.Office.Interop.Excel; 

 //Excel Automation variables:
 Excel.Application xlApp;
 Excel.Workbook xlBook;
 Excel.Worksheet xlSheet1, xlSheet2, xlSheet3;
 //Excel event delegate variables:
 Excel.AppEvents_WorkbookBeforeCloseEventHandler EventDel_BeforeBookClose;
 Excel.DocEvents_ChangeEventHandler EventDel_CellsChange;
 private void StartExcelAndSinkEvents()
 {
 //Start Excel, and then create a new workbook.
 xlApp = new Excel.Application();
 xlBook = xlApp.Workbooks.Add( Missing.Value );
 xlBook.Windows.get_Item(1).Caption = "XL Event Test";
 xlSheet1 = (Excel.Worksheet)xlBook.Worksheets.get_Item(1);
 xlSheet2 = (Excel.Worksheet)xlBook.Worksheets.get_Item(2);
 xlSheet3 = (Excel.Worksheet)xlBook.Worksheets.get_Item(3);
 xlSheet1.Activate();
 //Add an event handler for the WorkbookBeforeClose Event of the
 //Application object.
 EventDel_BeforeBookClose =
 new Excel.AppEvents_WorkbookBeforeCloseEventHandler( BeforeBookClose);
 xlApp.WorkbookBeforeClose += EventDel_BeforeBookClose;
 //Add an event handler for the Change event of both worksheet objects.
 EventDel_CellsChange = new Excel.DocEvents_ChangeEventHandler( CellsChange);
 xlSheet1.Change += EventDel_CellsChange;
 xlSheet2.Change += EventDel_CellsChange;
 xlSheet3.Change += EventDel_CellsChange;
 //Make Excel visible and give the user control.
 xlApp.Visible = true;
 xlApp.UserControl = true;
 }
 private void CellsChange(Excel.Range Target )
 {
 //This is called when any cell on a worksheet is changed.
 Debug.WriteLine("Delegate: You Changed Cells " +
 Target.get_Address( Missing.Value, Missing.Value,
 Excel.XlReferenceStyle.xlA1, Missing.Value, Missing.Value ) +
 " on " + Target.Worksheet.Name);
 }
 private void BeforeBookClose(Excel.Workbook Wb, ref bool Cancel )
 {
 //This is called when you choose to close the workbook in Excel.
 //The event handlers are removed, and then the workbook is closed
 //without saving the changes.
 Wb.Saved = true;
 Debug.WriteLine("Delegate: Closing the workbook and removing event handlers.");
 xlSheet1.Change -= EventDel_CellsChange;
 xlSheet2.Change -= EventDel_CellsChange;
 xlSheet3.Change -= EventDel_CellsChange;
 xlApp.WorkbookBeforeClose -= EventDel_BeforeBookClose;
 }