using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Threading;

public class Program

{

    public static void Main()

    {

        var stopwatch = Stopwatch.StartNew();

        var ienumerable = Iterator();

        Console.WriteLine($"Direct Assignment From Iterator: {stopwatch.ElapsedMilliseconds} ms");

        Console.WriteLine();

        stopwatch.Restart();

        var toList = Iterator().ToList();

        Console.WriteLine($"Iterator ToList: {stopwatch.ElapsedMilliseconds} ms");

        stopwatch.Restart();

        var any = Iterator().Any();

        Console.WriteLine($"Iterator Any: {stopwatch.ElapsedMilliseconds} ms");

        stopwatch.Restart();

        var countLinq = Iterator().Count();

        Console.WriteLine($"Iterator Count LINQ: {stopwatch.ElapsedMilliseconds} ms");

        Console.WriteLine();

        stopwatch.Restart();

        var ienumerableToList = Iterator().ToList();

        Console.WriteLine($"IEnumerable ToList: {stopwatch.ElapsedMilliseconds} ms");

        stopwatch.Restart();

        var ienumerableAny = Iterator().Any();

        Console.WriteLine($"IEnumerable Any: {stopwatch.ElapsedMilliseconds} ms");

        stopwatch.Restart();

        var ienumerableCountLinq = Iterator().Count();

        Console.WriteLine($"IEnumerable Count LINQ: {stopwatch.ElapsedMilliseconds} ms");

        Console.WriteLine();

        stopwatch.Restart();

        var listToList = toList.ToList();

        Console.WriteLine($"List ToList: {stopwatch.ElapsedMilliseconds} ms");

        stopwatch.Restart();

        var listAnyLinq = toList.Any();

        Console.WriteLine($"List Any LINQ: {stopwatch.ElapsedMilliseconds} ms");

​

        stopwatch.Restart();

        var listCountLinq = toList.Count();

        Console.WriteLine($"List Count LINQ: {stopwatch.ElapsedMilliseconds} ms");

        stopwatch.Restart();

        var countProperty = toList.Count;

        Console.WriteLine($"List Count Property: {stopwatch.ElapsedMilliseconds} ms");

    }

    private static IEnumerable<int> Iterator()

    {

        // simulates setup

        //Thread.Sleep(100);

        for (int i = 0; i < 5; i++)

        {

            // simulates overhead

            //Thread.Sleep(100);

            yield return i;

        }

        // simulates cleanup

        //Thread.Sleep(100);

    }

    // 

    private static List<int> FunctionWithListReturnType()

    {

        var list = new List<int>();

        foreach (var item in Iterator())

        {

            list.Add(item);

        }

        return list;

    }

}