using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var a = GenerateRandomCharsWithoutYield();

        Console.WriteLine(a);

        var b = GenerateRandomCharsWithYield().ToArray();

        Console.WriteLine(new string(b));

    }

    private static string GenerateRandomCharsWithoutYield()

    {

        Random rand = new Random();

        var arr = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

        var result = new char[6];

​

        for (int i = 0; i < result.Length; i++)

        {

            result[i] = arr[rand.Next(arr.Length)];

        }

​

        return new string(result);

    }

    public static IEnumerable<char> GenerateRandomCharsWithYield()

    {

        // Only usefull when processing > 10k tokens

        // saves on memory footprint, bc entire string does not stay in memory

        Random rand = new Random();

        var arr = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

​

        for (int i = 0; i < 6; i++)

        {

            yield return arr[rand.Next(arr.Length)];

        }

    }

}