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 验证IP合法性

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            try

            {

                string[] format = new string[4];

                string s = ".";

                format = textBox1.Text.Split(s.ToCharArray(), 4);

                for (int i = 0; i < 4; i++)

                {

                    if (Convert.ToInt32(format[i]) >= 255)

                    {

                        MessageBox.Show("IP地址不合法");

                        if (Convert.ToInt32(format[i]) <= 255)

                        {

                            MessageBox.Show("IP地址正确");

                        }

                    }

                    MessageBox.Show("IP地址正确");

                }

            }

            catch

            {

                MessageBox.Show("IP地址不合法");

            }

        }

        private void Form1_Load(object sender, EventArgs e)

        {

        }

    }

}