using System;

using System.Collections.Generic;

using System.Net;

using System.Net.NetworkInformation;

using System.Threading.Tasks;

using System.Threading.Tasks.Dataflow;

using System.Text.RegularExpressions;

using System.Linq;

using System.Globalization;

​

public class Program

{

    private static List<IPStatus> _results;

    public static async Task MyMethodAsync(IPAddress ip)

    {

        await Task.Delay(500);

        Console.WriteLine("processing");

    }

​

    public static async Task Asd()

    {

        var options = new ExecutionDataflowBlockOptions{MaxDegreeOfParallelism = 2};

        var block = new ActionBlock<IPAddress>(ip => MyMethodAsync(ip), options);

        var list = new List<IPAddress>{IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback};

        foreach (var ip in list)

        {

            block.Post(ip);

        }

​

        block.Complete();

        await block.Completion;

    }

​

    public static void Main()

    {

        char[] a = new char[] { 'a', 'b', 'c', 'd', 'e'};

        string str = new string(a);

        int index = str.IndexOf('a');

        str=str.Remove(index,1);

        a = str.ToCharArray();

        Console.WriteLine(a);

      }

}