登录系统

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 _01
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            label4.Visible = false;
            label5.Visible = false;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            label4.Visible = false;
            label5.Visible = false;
            label6.Visible = false;
            string a = "123", a1 = "123";
            textBox1.Text = textBox1.Text.Trim();
            textBox2.Text = textBox2.Text.Trim();
            label4.Visible = (textBox1.Text == "") ? true : false;
            if (label4.Visible == false)
            {
                label5.Visible = (textBox2.Text == "") ? true : false;
            }
            if (label4.Visible == false && label5.Visible == false)
            {
                bool con = (textBox1.Text == a && textBox2.Text == a1) ? true : false;
                label6.ForeColor = con ? Color.Green : Color.Red;
                label6.Text = con ? "登录成功" : "账号或密码错误";
                label6.Visible = true;
            }
        }
    }
}