06、C#异常处理

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

namespace _09
{
    public partial class Form1 : Form
    {
        private object textbox4;

        public Form1()
        {
            InitializeComponent();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                int x, y, res;
                x = int.Parse(textBox3.Text);
                y = int.Parse(textBox4.Text);

                switch (comboBox2.Text)
                {
                    case "+":
                        res = x + y;
                        break;
                    case "-":
                        res = x - y;
                        break;
                    case "*":
                        res = x * y;
                        break;
                    case "/":
                        res = x / y;
                        break;
                    default:
                        res = 9999;
                        break;
                }

                label4.Text = res.ToString();
                if (res > 10)
                    throw new ApplicationException("throw抛出的异常");

            }
            catch (FormatException fe)
            {
                MessageBox.Show(fe.Message);
                return;
            }
            catch (OverflowException ofe)
            {

                MessageBox.Show(ofe.Message);
                return;
            }
            catch (DivideByZeroException dze)
            {

                MessageBox.Show(dze.Message);
                return;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
                return;
            }
            finally
            {
                MessageBox.Show("最后者会执行");
            }
            }
    }
}