Handling CancelKeyPress using a CancellationToken

Console applications sometimes need to detect when they are closing to perform cleanup. Console.CancelKeyPress lets you register a callback when the user presses Ctrl+C or Ctrl+Break. This event can prevent the application from closing immediately, giving you a few seconds to clean up before actually terminating. This post shows how to use Console.CancelKeyPress to create a CancellationToken that cancels ongoing asynchronous operations.

public class Program
{
    public static async Task Main(string[] args)
    {
        using var cts = new CancellationTokenSource();
        Console.CancelKeyPress += (sender, e) =>
        {
            // We'll stop the process manually by using the CancellationToken
            e.Cancel = true;

            // Change the state of the CancellationToken to "Canceled"
            // - Set the IsCancellationRequested property to true
            // - Call the registered callbacks
            cts.Cancel();
        };

        await MainAsync(args, cts.Token);
    }

    private static async Task MainAsync(string[] args, CancellationToken cancellationToken)
    {
        try
        {
            // code using the cancellation token
            Console.WriteLine("Waiting");
            await Task.Delay(10_000, cancellationToken);
        }
        catch (OperationCanceledException)
        {
            Console.WriteLine("Operation canceled");
        }
    }
}

If you need to handle more cases beyond CancelKeyPress, see the post about detecting console closing in .NET, which uses the SetConsoleCtrlHandler method to detect when the console is closing.

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