using System;

using System.Collections.Generic;

using System.Threading;

using System.Threading.Tasks;

​

public class CancellationExample

{

    public static async Task Main()

    {

        var random = new Random();

        using var cts = new CancellationTokenSource();

        CancellationToken token = cts.Token;

        var timer = new Timer(Elapsed, cts, 5000, Timeout.Infinite);

​

        var task = Task.Run(

            async () =>

            {

                var product33 = new List<int>();

                for (int index = 1; index < short.MaxValue; index++)

                {

                    if (token.IsCancellationRequested)

                    {

                        Console.WriteLine("\nCancellation requested in antecedent...\n");

                        token.ThrowIfCancellationRequested();

                    }

                    if (index % 2000 == 0)

                    {

                        await Task.Delay(5);

                    }

                    if (index % 33 == 0)

                    {

                        product33.Add(index);

                    }

                }

​

                return product33.ToArray();

            }, token);

​

        Task continuation = task.ContinueWith(

            async antecedent =>

            {

                Console.WriteLine("Multiples of 33:\n");

                int[] array = antecedent.Result;

                for (int index = 0; index < array.Length; index++)

                {

                    if (token.IsCancellationRequested)

                    {

                        Console.WriteLine("\nCancellation requested in continuation...\n");

                        token.ThrowIfCancellationRequested();

                    }

                    if (index % 100 == 0)

                    {

                        int delay = random.Next(5, 50);

                        await Task.Delay(delay);

                    }

​

                    Console.Write($"{array[index]:N0}{(index != array.Length - 1 ? ", " : "")}");

​

                    if (Console.CursorLeft >= 74)

                    {

                        Console.WriteLine();

                    }

                }

                Console.WriteLine();

            }, token);

​

        try

        {

            await continuation;

        }

        catch (TaskCanceledException ex)

        {

            Console.WriteLine(ex.Message);

        }

​

        Console.WriteLine("\nAntecedent Status: {0}", task.Status);

        Console.WriteLine("Continuation Status: {0}", continuation.Status);

    }

​

    static void Elapsed(object state)

    {

        if (state is CancellationTokenSource cts)

        {

            cts.Cancel();

            Console.WriteLine("\nCancellation request issued...\n");

        }

    }

}

// The example displays the following output:

//    Multiples of 33:

//

//    33, 66, 99, 132, 165, 198, 231, 264, 297, 330, 363, 396, 429, 462, 495, 528,

//    561, 594, 627, 660, 693, 726, 759, 792, 825, 858, 891, 924, 957, 990, 1,023,

//    1,056, 1,089, 1,122, 1,155, 1,188, 1,221, 1,254, 1,287, 1,320, 1,353, 1,386,

//    1,419, 1,452, 1,485, 1,518, 1,551, 1,584, 1,617, 1,650, 1,683, 1,716, 1,749,

//    1,782, 1,815, 1,848, 1,881, 1,914, 1,947, 1,980, 2,013, 2,046, 2,079, 2,112,

//    2,145, 2,178, 2,211, 2,244, 2,277, 2,310, 2,343, 2,376, 2,409, 2,442, 2,475,

//    2,508, 2,541, 2,574, 2,607, 2,640, 2,673, 2,706, 2,739, 2,772, 2,805, 2,838,

//    2,871, 2,904, 2,937, 2,970, 3,003, 3,036, 3,069, 3,102, 3,135, 3,168, 3,201,

//    3,234, 3,267, 3,300, 3,333, 3,366, 3,399, 3,432, 3,465, 3,498, 3,531, 3,564,

//    Cancellation requested in continuation...

//

//

//    Cancellation request issued...

//

//    TaskCanceledException: A task was canceled.

//

//    Antecedent Status: RanToCompletion

//    Continuation Status: Canceled

​