C # opens Excel and responds to client automation events

Using System;
Using System.Collections.Generic;
Using System.ComponentModel;
Using System.Data;
Using System.Diagnostics;
Using System.Drawing;
Using System.Linq;
Using System.Text;
Using System.Threading.Tasks;
Using System.Windows.Forms;

Using MSExcel = Microsoft.Office.Interop.Excel;

namespace Word
{
public partial class Form1:form
{
Public Form1 ()
{
InitializeComponent ();
}
private void Form1_Load (object sender, EventArgs e)
{
}
Msexcel.application Excelapp;
Msexcel.workbook Book;


private void Button1_Click (object sender, EventArgs e)
{
OpenFileDialog p_getfile = new OpenFileDialog ();
DialogResult p_dr = P_getfile.showdialog ();
Object obj = (object) (P_getfile.filename);
if (p_dr = = DialogResult.OK)
{
Excelapp = new Msexcel.application ();
Book = EXCELAPP.APPLICATION.WORKBOOKS.ADD (obj);
Excelapp.visible = true;
}
Excelapp.workbookbeforesave + = new Msexcel.appevents_workbookbeforesaveeventhandler (excelApp_WorkbookBeforeSave);
}
private void Excelapp_workbookbeforesave (Msexcel.workbook Wb, bool SaveAsUi, ref bool Cancel)
{
MessageBox.Show ("Hello Excel");
}
}
}

C # opens Excel and responds to client automation events