C#【控件篇】组件ErrorProvider的使用

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

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            if (textBox1.Text.Length < 8 || textBox1.Text.Length > 15)
            {
                errorProvider1.SetError(textBox1, "请输入8-15位字母和数字");
                errorProvider1.Icon = new Icon(@"D:\Desktop\WindowsFormsApp1\WindowsFormsApp1\bin\Debug\error.ico");
            }
            else
            {
                errorProvider1.SetError(textBox1,"");
                errorProvider1.Icon = new Icon(@"D:\Desktop\WindowsFormsApp1\WindowsFormsApp1\bin\Debug\ok.ico");

            }
        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            if (textBox2.Text.Length < 8 || textBox2.Text.Length > 15)
            {
                errorProvider1.SetError(textBox2, "请输入8-15位字母和数字");
                errorProvider1.Icon = new Icon(@"D:\Desktop\WindowsFormsApp1\WindowsFormsApp1\bin\Debug\error.ico");
            }
            else
            {
                errorProvider1.SetError(textBox2, "符合要求");
                errorProvider1.Icon = new Icon(@"D:\Desktop\WindowsFormsApp1\WindowsFormsApp1\bin\Debug\ok.ico");

            }
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {
            if (textBox3.Text!=textBox2.Text)
            {
                errorProvider1.SetError(textBox3, "两次输入的密码不一致");
                errorProvider1.Icon = new Icon(@"D:\Desktop\WindowsFormsApp1\WindowsFormsApp1\bin\Debug\error.ico");
            }
            else
            {
                errorProvider1.SetError(textBox3, "通过验证");
                errorProvider1.Icon = new Icon(@"D:\Desktop\WindowsFormsApp1\WindowsFormsApp1\bin\Debug\ok.ico");

            }
        }
    }
}

界面控件如下：