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 IP {   public delegate void FallBackEvent(IpInputBox box, int flag);    public partial class Dialog : Form   {     public Dialog()     {       InitializeComponent();     }      private void Form1_Load(object sender, EventArgs e)     {       this.Controls.Add(ipBox);       ipBox.Location = new Point(10,10);     }      private IpInputBox ipBox = new IpInputBox(false);   } } 

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows.Forms; using System.Drawing;  namespace IP {   public class IpInputBox :TextBox   {     private bool _isNetmask = false;     public bool IsNetmask     {       get { return _isNetmask; }       set { _isNetmask = value; }     }     public IpInputBox(bool isNetmask)     {       _isNetmask = isNetmask;        this.Size = new System.Drawing.Size(150, 25);        _dotLabel1.Text = ".";       _dotLabel2.Text = ".";       _dotLabel3.Text = ".";        _dotLabel1.Size = new System.Drawing.Size(10, 25);       _dotLabel2.Size = new System.Drawing.Size(10, 25);       _dotLabel3.Size = new System.Drawing.Size(10, 25);        _box1.IsNetmask = _isNetmask;       _box2.IsNetmask = _isNetmask;       _box3.IsNetmask = _isNetmask;       _box4.IsNetmask = _isNetmask;        _box1.Flag = 1;       _box2.Flag = 2;       _box3.Flag = 3;       _box4.Flag = 4;         this.Controls.Add(_box1);       this.Controls.Add(_dotLabel1);         this.Controls.Add(_box2);       this.Controls.Add(_dotLabel2);         this.Controls.Add(_box3);       this.Controls.Add(_dotLabel3);        this.Controls.Add(_box4);        this.Font = new System.Drawing.Font(this.Font.Name, 11);       _box1.Location = new System.Drawing.Point(-1, 2);       _dotLabel1.Location = new System.Drawing.Point(29, 2);       _box2.Location = new System.Drawing.Point(39, 2);       _dotLabel2.Location = new System.Drawing.Point(69, 2);       _box3.Location = new System.Drawing.Point(79, 2);       _dotLabel3.Location = new System.Drawing.Point(109, 2);       _box4.Location = new System.Drawing.Point(119, 2);        _box1.Box = this;       _box2.Box = this;       _box3.Box = this;       _box4.Box = this;     }     public void FallBackEventFun(IpInputBox box, int flag)     {       switch (flag)       {         case 1:           _box1.Focus();           break;         case 2:           _box1.Focus();           break;         case 3:           _box2.Focus(); ;           break;         case 4:           _box3.Focus(); ;           break;       }     }      private string _ipAddress = string.Empty;     public void UpDateIpaddress()     {       try       {         string[] sArray = ipAddress.Split(new char[] { '.' });         _box1.Text = sArray[0];         _box2.Text = sArray[1];         _box3.Text = sArray[2];         _box4.Text = sArray[3];       }       catch (Exception exp)       {         MessageBox.Show("更新字符串失敗:" + exp.Message);       }     }      /// <summary>     /// 獲取ip地址     /// </summary>     public string IpAddressString     {       get       {         string _ipStr1 = _box1.Text;         string _ipStr2 = _box2.Text;         string _ipStr3 = _box3.Text;         string _ipStr4 = _box4.Text;         string _ipDotStr = ".";         _ipAddress = _ipStr1 + _ipDotStr + _ipStr2 + _ipDotStr + _ipStr3 + _ipDotStr + _ipStr4;         return _ipAddress;       }       set       {         _ipAddress = value;       }     }     private string ipAddress = string.Empty;      public string IpAddress     {       get { return ipAddress; }       set { ipAddress = value; }     }      private SubIpInputBox _box1 = new SubIpInputBox("");     private SubIpInputBox _box2 = new SubIpInputBox("");     private SubIpInputBox _box3 = new SubIpInputBox("");     private SubIpInputBox _box4 = new SubIpInputBox("");      private Label _dotLabel1 = new Label();     private Label _dotLabel2 = new Label();     private Label _dotLabel3 = new Label();    } } 

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Drawing; using System.Windows.Forms;  namespace IP {   public class SubIpInputBox:TextBox   {       /// <summary>       /// 判斷是否是子網掩碼,false表示ip地址,true表示子網掩碼       /// </summary>       private bool _isNetmask = false;       private bool _isSendKey = false;       private System.ComponentModel.IContainer components;       private int _flag = 0;        public int Flag       {         get { return _flag; }         set { _flag = value; }       }        /// <summary>       ///        /// </summary>       public event FallBackEvent TextFallBackEvent;         //定義事件函數       public void FallBackEventFun(int flag)       {         if (TextFallBackEvent != null)         {           TextFallBackEvent(box, this.Flag);         }       }        public bool IsNetmask       {         get { return _isNetmask; }         set { _isNetmask = value; }       }        /// <summary>       /// 構造函數       /// </summary>       public SubIpInputBox(bool isNetmask)       {         _isNetmask = isNetmask;         box = new IpInputBox(_isNetmask);         this.Font = new System.Drawing.Font(this.Font.Name, 11);         this.BorderStyle = System.Windows.Forms.BorderStyle.None;//去掉邊框         this.TextAlign = HorizontalAlignment.Center;//字體居中         this.Size = new System.Drawing.Size(30, 25);         this.MaxLength = 3;       }        public SubIpInputBox(string str)       {         this.Text = str;         this.Size = new System.Drawing.Size(30, 25);         this.MaxLength = 3;         this.BorderStyle = System.Windows.Forms.BorderStyle.None;//去掉邊框         this.TextAlign = HorizontalAlignment.Center;//字體居中       }        private IpInputBox box;       public IpInputBox Box       {         get { return box; }         set { box = value; }       }        protected override void OnKeyUp(KeyEventArgs e)       {         base.OnKeyUp(e);           if (this.Text == "")         {           if (e.KeyCode.ToString() == "Back")           {             this.TextFallBackEvent += new FallBackEvent(box.FallBackEventFun);             this.FallBackEventFun(this.Flag);           }         }       }       protected override void OnKeyPress(KeyPressEventArgs e)       {         base.OnKeyPress(e);          //阻止從鍵盤輸入鍵         e.Handled = true;           if ((e.KeyChar >= '0' && e.KeyChar <= '9') || (e.KeyChar == (char)8))         {            if ((e.KeyChar == (char)8))           {             e.Handled = false; return;           }           else           {             int len = this.Text.Length;             if (len < 4)             {               if (len == 0 && e.KeyChar != '0')               {                 e.Handled = false; return;               }               else if (len == 0)               {                 if (this.Flag == 1 && this.IsNetmask == false)                 {                   return;                 }               }               e.Handled = false; return;             }             else             {               // MessageBox.Show("編號最多只能輸入3位數字！");             }           }         }         else if (e.KeyChar == '.')         {           //MessageBox.Show("編號只能輸入數字！");           if (this.Text.Length != 0)           {             // 如果輸入 . 就執行 TAB 鍵              SendKeys.SendWait("{TAB}");           }         }         else if (this._isSendKey)         {           this.SelectAll();         }        }         protected override void OnTextChanged(EventArgs e)       {          try         {           string currentStr = this.Text;           int currentNumber = Convert.ToInt32(currentStr);           this.Text = currentNumber.ToString();           this.SelectionStart = currentStr.Length;//設置光標在末尾           if (_isNetmask == false)//表示ip地址           {              if (currentNumber > 223 || (currentNumber == 0 && this.Flag == 1))             {               MessageBox.Show("你輸入的" + currentStr + "不是有效數值，請指定一個介于1到223之間的數值!", "錯誤", MessageBoxButtons.OK, MessageBoxIcon.Warning);                if (this.Flag == 1 && currentNumber == 0)               {                 this.Text = "1";               }               else               {                 this.Text = "223";               }               _isSendKey = true;               this.Focus();               this.SelectionStart = currentStr.Length;//設置光標在末尾               this.SelectAll();             }             else             {               if (currentStr.Length == 3 && _isSendKey == false)               {// 當輸入的字符個數為3時，跳入另外一個輸入框                 //MessageBox.Show("輸入完畢");                 if (currentNumber == 0)                 {                   this.Text = "";                   MessageBox.Show("000");                 }                 SendKeys.SendWait("{TAB}");               }             }            }           else//子網掩碼           {             if (currentNumber > 255)             {               MessageBox.Show("你輸入的" + currentStr + "不是有效數值，請指定一個介于0到255之間的數值!", "錯誤", MessageBoxButtons.OK, MessageBoxIcon.Warning);               this.Text = "255";               this.Focus();               this.SelectionStart = currentStr.Length;//設置光標在末尾               this.SelectAll();             }             else             {               if (currentStr.Length == 3 && _isSendKey == false)               {// 當輸入的字符個數為3時，跳入另外一個輸入框                 //MessageBox.Show("輸入完畢");                 SendKeys.SendWait("{TAB}");                }             }           }         }         catch         {           // 異常處理         }       }        private void InitializeComponent()       {         this.SuspendLayout();         //          // SubIpInputBox         //          this.TabIndexChanged += new System.EventHandler(this.SubTextBox_TabIndexChanged);         this.ResumeLayout(false);       }       private void SubTextBox_TabIndexChanged(object sender, EventArgs e)       {        }   } }