C# 显示excel的最大数据行数

using System;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using Microsoft.VisualStudio.Tools.Applications.Runtime;
using Excel = Microsoft.Office.Interop.Excel;
using Office = Microsoft.Office.Core;

namespace ExcelWorkbook1
{
    public partial class Sheet1
    {
        private void Sheet1_Startup(object sender, System.EventArgs e)
        {
        }

        private void Sheet1_Shutdown(object sender, System.EventArgs e)
        {
        }

        #region VSTO 设计器生成的代码

        /// <summary>
        /// 设计器支持所需的方法 - 不要
        /// 使用代码编辑器修改此方法的内容。
        /// </summary>
        private void InternalStartup()
        {
            this.button1.Click += new System.EventHandler(this.button1_Click);
            this.namedRange1.Change += new Microsoft.Office.Interop.Excel.DocEvents_ChangeEventHandler(this.namedRange1_Change);
            this.Shutdown += new System.EventHandler(this.Sheet1_Shutdown);
            this.Startup += new System.EventHandler(this.Sheet1_Startup);

        }

        #endregion

        private void button1_Click(object sender, EventArgs e)
        {
           Excel.Worksheet ws;
            int l;
            ws = (Excel.Worksheet)Globals.ThisWorkbook.Worksheets["sheet1"];
            l = ws.Application.get_Range("A65536", missing).get_End(Excel.XlDirection.xlUp).Row;
            MessageBox.Show(l.ToString());
 
        }

1.(Excel.Worksheet)不可省略;
2.missing不可缺少;ToString()后面的括号不能少;
3.get_End(Excel.XlDirection.xlUp).Row相对于VBA好啰嗦啊