c#写计算器的源代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        private ToolStripStatusLabel label;
        private ToolStripComboBox bb;
        string s;
        Button btn, btn1;
        double x, y;
        public Form1()
        {
            InitializeComponent();

        }

        private void Form1_Load(object sender, EventArgs e)
        {
            菜单栏ToolStripMenuItem.Click += heihei;
            button23.Visible = false;
            
            textBox1.Text = "";
            label1.Text = "";

           
            label = new ToolStripStatusLabel(DateTime.Now.ToString());
            bb = new ToolStripComboBox();
            statusStrip1.Items.Add(bb);
            statusStrip1.Items.Add(label);
            bb.Items.Add("北京");
            bb.Items.Add("莫斯科");
            bb.Items.Add("巴黎");
            bb.Items.Add("纽约");
            bb.SelectedIndex = 0;
            timer1.Tick += time;
            timer1.Interval = 1000;

            中mToolStripMenuItem.Checked = true;
            大bToolStripMenuItem.Click += haha;
            小sToolStripMenuItem.Click += haha;
            中mToolStripMenuItem.Click += haha;
            大bToolStripMenuItem.Checked=false;
            小sToolStripMenuItem.Checked = false;

        }
        private void haha(object sender, EventArgs e)
        {
           ToolStripMenuItem sen = sender as ToolStripMenuItem;
           if (sen == 大bToolStripMenuItem)
           {
               大bToolStripMenuItem.Checked = true;
               this.Size = new Size(800, 450);
            中mToolStripMenuItem.Checked =false;
             小sToolStripMenuItem.Checked=false;