using System;

using System.Threading;

using System.Threading.Tasks;

​

public class Program

{

    public static void Main()

    {

        try

        {

            var cts = new CancellationTokenSource();

            Console.WriteLine("Before starting task");

            var task = Task.Run(() => DoSomething(cts.Token), cts.Token);

            Thread.Sleep(2000);

            Console.WriteLine("Before cancelling task");

            cts.Cancel();

            //task.Wait(); // if this is commented, the task will not run to completion

            cts.Dispose();

            Thread.Sleep(2000);

        }

        catch (Exception ex)

        {

            Console.WriteLine("Exception caught", ex);

        }

    }

​

    private static async Task DoSomething(CancellationToken ct)

    {

        while (!ct.IsCancellationRequested)

        {

            await Task.Delay(3000);

            Console.WriteLine("Hello World");

        }

        if(ct.IsCancellationRequested) Console.WriteLine("erik is cool.");

    }

}