using System;

using System.Text;

public class Program {

  public static void Main() {

​

    StringBuilder sb = new StringBuilder();

    // Append Method

    sb.Append("Welcome to the C# Course!");

​

    Console.WriteLine(sb.ToString());

    // insert

    sb.Insert(0, "Hello user. ");

    Console.WriteLine(sb.ToString());

​

    //remove

    sb.Remove(5, 5);

    Console.WriteLine(sb.ToString());

​

    //replace

    sb.Replace('!', ' ');

    Console.WriteLine(sb.ToString());

​

  }

}