using System;

using System.Diagnostics;

using System.Text.RegularExpressions;

using System.Linq;

​

public class Program

{

    private static bool is_only_eng_letters_and_digits(string str)

    {

        foreach (char ch in str)

        {

            if (!(ch >= 'A' && ch <= 'Z') && !(ch >= 'a' && ch <= 'z') && !(ch >= '0' && ch <= '9'))

            {

                return false;

            }

        }

​

        return true;

    }

​

    private static readonly Regex r_only_eng_ch = new Regex(@"^[A-Z0-9]+$", RegexOptions.CultureInvariant | RegexOptions.IgnoreCase | RegexOptions.Compiled);

    private static bool is_only_eng_letters_and_digits_LINQ(string str)

    {

        return str.All(ch => (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9'));

    }

​

    public static void Main()

    {

        Stopwatch sw = new Stopwatch();

        string eng_str = "qwerty123";

        string rus_str = "qwertyФЫВА123";

        sw.Start();

        for (int i = 0; i < 100000; i++)

        {

            is_only_eng_letters_and_digits(eng_str);

        }

​

        sw.Stop();

        Console.WriteLine("Cycle time with english string: " + sw.ElapsedMilliseconds + " ms.");

        sw.Reset();

        sw.Start();

        for (int i = 0; i < 100000; i++)

        {

            is_only_eng_letters_and_digits(rus_str);

        }

​

        sw.Stop();

        Console.WriteLine("Cycle time with russian string: " + sw.ElapsedMilliseconds + " ms.");

        sw.Reset();

        sw.Start();

        for (int i = 0; i < 100000; i++)

        {

            r_only_eng_ch.IsMatch(eng_str);

        }

​

        sw.Stop();

        Console.WriteLine("Regex time with english string: " + sw.ElapsedMilliseconds + " ms.");

        sw.Reset();

        sw.Start();

        for (int i = 0; i < 100000; i++)

        {

            r_only_eng_ch.IsMatch(rus_str);

        }

​

        sw.Stop();

        Console.WriteLine("Regex time with russian string: " + sw.ElapsedMilliseconds + " ms.");

        sw.Reset();

        sw.Start();

        for (int i = 0; i < 100000; i++)

        {

            is_only_eng_letters_and_digits_LINQ(eng_str);

        }

​

        sw.Stop();

        Console.WriteLine("LINQ time with english string: " + sw.ElapsedMilliseconds + " ms.");

        sw.Reset();

        sw.Start();

        for (int i = 0; i < 100000; i++)

        {

            is_only_eng_letters_and_digits_LINQ(rus_str);

        }

​

        sw.Stop();

        Console.WriteLine("LINQ time with russian string: " + sw.ElapsedMilliseconds + " ms.");

    }

}