vb วิธีการตัดขอความให้แสดงเท่าที่กำหนดเอง อย่างเช่น ข้อความ xxxxxxxxxxxx ถ้า xxxxx มากกว่า 10 ตัว ให้แสดง ให้แสดงตำแหน่งที่ 11 เป็น ... อย่างไรครับ

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

      

        private void textBox1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
            var s = textBox1.TextLength;
            MessageBox.Show(s.ToString());
            textBox3.Text = textBox1.Text;
            textBox2.Focus();
            }
  
        }
        private void textBox2_KeyDown(object sender, KeyEventArgs e)
        {
           var s =textBox2.Text;
            if (e.KeyCode == Keys.Enter)
            {
                string str = textBox1.Text.Substring(0, Convert.ToInt32(s));
                string etc = textBox1.Text.Substring(Convert.ToInt32(s),textBox1.Text.Length-Convert.ToInt32(s));
                string dot = "";
                for (int i = 0;i < etc.Length; i++)
                {
                    dot += etc.Substring(i, etc.Length - i).Replace(etc.Substring(i, etc.Length-i), ".");  
                }
                textBox3.Clear();
                textBox3.Text = str+dot;
            }
        }

       
    }
}

Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Linq
Imports System.Text
Imports System.Windows.Forms

Namespace TEXTSUB
	Public Partial Class Form1
		Inherits Form
		Public Sub New()
			InitializeComponent()
		End Sub



		Private Sub textBox1_KeyDown(sender As Object, e As KeyEventArgs)
			If e.KeyCode = Keys.Enter Then
				Dim s = textBox1.TextLength
				MessageBox.Show(s.ToString())
				textBox3.Text = textBox1.Text
				textBox2.Focus()
			End If

		End Sub
		Private Sub textBox2_KeyDown(sender As Object, e As KeyEventArgs)
			Dim s = textBox2.Text
			If e.KeyCode = Keys.Enter Then
				Dim str As String = textBox1.Text.Substring(0, Convert.ToInt32(s))
				Dim etc As String = textBox1.Text.Substring(Convert.ToInt32(s), textBox1.Text.Length - Convert.ToInt32(s))
				Dim dot As String = ""
				For i As Integer = 0 To etc.Length - 1
					dot += etc.Substring(i, etc.Length - i).Replace(etc.Substring(i, etc.Length - i), ".")
				Next
				textBox3.Clear()
				textBox3.Text = str & dot
			End If
		End Sub


	End Class
End Namespace