C#windows窗体程序

简易加法

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

namespace WindowsFormsApplication4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void label1_Click_1(object sender, EventArgs e)
        {

        }

        private void label2_Click(object sender, EventArgs e)
        {

        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (textBox1.Text.Length == 0 || textBox2.Text.Length == 0)
            {
                MessageBox.Show("请输入数!:");
                return;
            }

            try
            {
                double x = double.Parse(textBox1.Text);
                double y = double.Parse(textBox2.Text);
                textBox3.Text = (x + y).ToString();

            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }


        }
        }
    }

　　实现结果：