Use the following code :

C# Syntax (Toggle Plain Text)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = "";
            Sample a = new Sample();
            a.Refresh();   // re-paint a form
            do
            {
                s = Console.ReadLine();
                a.MyText = s;
                a.Refresh();  // re-paint a form
            } while (s.Length != 0);
        }
        static void show()
        {
 
        }
    }
}
 
class Sample : System.Windows.Forms.Form
{
    System.Windows.Forms.TextBox t = new System.Windows.Forms.TextBox();
    public Sample()
    {
        t.Multiline = true;
        t.Size = new System.Drawing.Size(100, 100);
        Controls.Add(t);
        Show();
    }
    public string MyText
    {
        get
        {
            return t.Text;
        }
        set
        {
            t.Text = t.Text + "\r" + "\n" + value;
        }
    }
 
}

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication5 { class Program { static void Main(string[] args) { string s = ""; Sample a = new Sample(); a.Refresh(); // re-paint a form do { s = Console.ReadLine(); a.MyText = s; a.Refresh(); // re-paint a form } while (s.Length != 0); } static void show() { } } } class Sample : System.Windows.Forms.Form { System.Windows.Forms.TextBox t = new System.Windows.Forms.TextBox(); public Sample() { t.Multiline = true; t.Size = new System.Drawing.Size(100, 100); Controls.Add(t); Show(); } public string MyText { get { return t.Text; } set { t.Text = t.Text + "\r" + "\n" + value; } } }