WinForm 按鈕使用

 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 WinForm2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string str1 = textBox1.Text;
            string str2 = textBox2.Text;
            int i1, i2;
            if (!int.TryParse(str1, out i1))
            {
                MessageBox.Show("text1 is not a real number");
                textBox1.Text = "";
                textBox2.Text = "";
                return;
            }
            if (int.TryParse(str2, out i2) == false)
            {
                MessageBox.Show("text2 is not a real number");
                textBox1.Text = "";
                textBox2.Text = "";
                return;
            }

            int i3 = i1 + i2;
            textBox3.Text = Convert.ToString(i3);
        }
    }
}