using System;

using System.Collections.Generic;

using System.Diagnostics;

public class Program {

    public static void Main() {

        List<int> list = new List<int>();

        for(var i = 0 ; i < 100000 ; i++) {

            list.Add(i);

        }

        Stopwatch sw = new Stopwatch();

        sw.Start();

        for(var i = 0 ; i < 10000 ; i++) ForEachList(list);

        sw.Stop();

        Console.WriteLine("foreach(var i in l) * 10000 {0}ms", sw.Elapsed);

        sw = new Stopwatch();

        sw.Start();

        for(var i = 0 ; i < 100 ; i++) ForList(list);

        sw.Stop();

        Console.WriteLine("for(var i = 0 ; i < l.Count ; i++) * 10000 {0}ms", sw.Elapsed);

        sw = new Stopwatch();

        sw.Start();

        for(var i = 0 ; i < 100 ; i++) IEnum(list);

        sw.Stop();

        Console.WriteLine("using (var i = l.GetEnumerator()) * 10000 {0}ms", sw.Elapsed);

    }

    public static void IEnum(IEnumerable<int> l) {

        var counter = 0;

        using (var i = l.GetEnumerator()) {

            while (i.MoveNext()) {

                counter += i.Current;

            }

        }

    }

    public static void ForList(List<int> l) {

        var counter = 0;

        for(var i = 0 ; i < l.Count ; i++) {

            counter += i;

        }

    }

    public static void ForEachList(List<int> l) {

        var counter = 0;

        foreach(var i in l) {

            counter += i;

        }

    }

}