using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading;

using System.Diagnostics;

public class Program

{

    public static void Main()

    {

        var numbers = new List<int> { 1, 2, 3, 4, 5 };

        var watch = Stopwatch.StartNew();

        var oddNumbers = new List<int>();

        //foreach execution

        foreach (var n in numbers) { Thread.Sleep(100);

                             if (n % 2 != 0) { oddNumbers.Add(n); } }

        watch.Stop();

        Console.WriteLine(watch.ElapsedMilliseconds);

        //LINQ query building

        watch = Stopwatch.StartNew();

        var oddNumbersLINQ = numbers.Where(n => { Thread.Sleep(100); 

                                          return (n % 2 != 0); });

        watch.Stop();

        Console.WriteLine(watch.ElapsedMilliseconds);

        numbers.Add(6);

        //LINQ Actual execution

        watch = Stopwatch.StartNew();

        List<int> abc = oddNumbersLINQ.ToList<int>();

                watch.Stop();

        Console.WriteLine(watch.ElapsedMilliseconds);

​

    }

}