using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

​

public class Program

{

        public void Main()

        {

            var rnd = new Random();

            var dummyDataForWarmup = Enumerable.Range(90, 20).ToList();

            var data = Enumerable.Range(0, 400000).Select(x => rnd.Next(0, 200)).ToList();

​

            Console.WriteLine("Warmup:");

            Console.WriteLine(TestLINQ(dummyDataForWarmup).ToString("G"));

            Console.WriteLine(TestForeach(dummyDataForWarmup).ToString("G"));

            Console.WriteLine(TestFor(dummyDataForWarmup).ToString("G"));

​

            Console.WriteLine();

            Console.WriteLine("Real run:");

            Console.WriteLine(TestLINQ(data).ToString("G"));

            Console.WriteLine(TestForeach(data).ToString("G"));

            Console.WriteLine(TestFor(data).ToString("G"));

​

            Console.ReadLine();

        }

​

        public static TimeSpan TestLINQ(IList<int> data)

        {

            GC.Collect();

            GC.WaitForPendingFinalizers();

​

            var sw = Stopwatch.StartNew();

​

            var query = from num in data where num < 100 select num;

            var count = query.Count();

​

            sw.Stop();

​

            Console.WriteLine("TestLINQ count: " + count);

​

            return sw.Elapsed;

        }

​

        public static TimeSpan TestForeach(IList<int> data)

        {

            GC.Collect();

            GC.WaitForPendingFinalizers();

​

            var sw = Stopwatch.StartNew();

​

            var searchResults = new List<int>(data.Count);

            foreach (var j in data)

            {

                if (j < 100)

                {

                    searchResults.Add(j);

                }

            }

            var count = searchResults.Count;

​

            sw.Stop();

​

            Console.WriteLine("TestForeach count: " + count);

​

            return sw.Elapsed;

        }

​

        public static TimeSpan TestFor(IList<int> data)

        {

            GC.Collect();

            GC.WaitForPendingFinalizers();

​

            var sw = Stopwatch.StartNew();

​

            var searchResults = new List<int>(data.Count);

            for (int index = 0; index < data.Count; index++)

            {

                if (data[index] < 100)

                {

                    searchResults.Add(data[index]);

                }

            }

            var count = searchResults.Count;

​

            sw.Stop();

​

            Console.WriteLine("TestFor count: " + count);

​

            return sw.Elapsed;

        }

}