using System;

using System.IO;

public class Program

{

    public static void Main()

    {

        for (int x = 0; x < 10; x++)

        {

            string output = GetRandomString(20);

            Console.WriteLine(output);

        }

    }

    static string GetRandomString(int lenOfTheNewStr)

    {

        string output = string.Empty;

        while (true)

        {

            output = output + Path.GetRandomFileName().Replace(".", string.Empty);

​

            if (output.Length > lenOfTheNewStr)

            {

                output = output.Substring(0, lenOfTheNewStr);

                break;

            }

        }

        return output;

    }

}