using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

​

namespace ConsoleApplication2

{

    public class Program

    {

​

        static readonly Random rand = new Random();

        const string Alphabet = "abcdefghijklmnopqrstuvwyxzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.+-*/";

        private const string Numbers = "0123456789i.+";

​

        public static void Main()

        {

            Benchmark(100);

            Benchmark(1000);

            Benchmark(10000);

            Benchmark(100000);

            Benchmark(1000000);

        }

​

        private static void Benchmark(int sampleSize)

        {

            var mostlyInvalidInput = GenerateListOfRandomStrings(sampleSize, Alphabet);

​

            var stopwatch1 = Stopwatch.StartNew();

            foreach (var s in mostlyInvalidInput)

            {

                IsValidStringOrig(s);

            }

            stopwatch1.Stop();

​

            var stopwatch2 = Stopwatch.StartNew();

            foreach (var s in mostlyInvalidInput)

            {

                IsValidStringLinq(s);

            }

            stopwatch2.Stop();

​

            var mostlyValidInput = GenerateListOfRandomStrings(sampleSize, Numbers);

            var stopwatch3 = Stopwatch.StartNew();

            foreach (var s in mostlyValidInput)

            {

                IsValidStringOrig(s);

            }

            stopwatch3.Stop();

​

            var stopwatch4 = Stopwatch.StartNew();

            foreach (var s in mostlyValidInput)

            {

                IsValidStringLinq(s);

            }

            stopwatch4.Stop();

​

            Console.WriteLine("Sample Size: {0}", sampleSize);

            Console.WriteLine("Original; Mostly Invalid: {0}ms", stopwatch1.ElapsedMilliseconds);

            Console.WriteLine("Linq; MostlyInvalid: {0}ms", stopwatch2.ElapsedMilliseconds);

            Console.WriteLine("Original; Mostly Valid: {0}ms", stopwatch3.ElapsedMilliseconds);

            Console.WriteLine("Linq; Mostly Valid: {0}ms", stopwatch4.ElapsedMilliseconds);

            Console.WriteLine();

        }

​

        private static List<string> GenerateListOfRandomStrings(int size, string alphabet)

        {

            var result = new List<string>();

            for (var i = 0; i < size; i++)

            {

                result.Add(GenerateString(10, alphabet));

            }

            return result;

        }

​

        static string GenerateString(int size, string alphabet)

        {

            char[] chars = new char[size];

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

            {

                chars[i] = alphabet[rand.Next(alphabet.Length)];

            }

            return new string(chars);

        }

​

        private static readonly char[] ValidChars = { '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '.', 'i' };

​

        private static bool IsValidStringOrig(string input)

        {

            var isValid = true;

            foreach (var c in input)

            {

                if (!ValidChars.Contains(c))

                {

                    isValid = false;

                }

            }

            return isValid;

        }

​

        private static bool IsValidStringLinq(string input)

        {

            return input.All(c => ValidChars.Contains(c));

        }

    }

}

​