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Console.CancelKeyPress Event

Occurs when the Control modifier key (Ctrl) and either the ConsoleKey.C console key (C) or the Break key are pressed simultaneously (Ctrl+C or Ctrl+Break).

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static event ConsoleCancelEventHandler CancelKeyPress

This event is used in conjunction with System.ConsoleCancelEventHandler and System.ConsoleCancelEventArgs. The CancelKeyPress event enables a console application to intercept the Ctrl+C signal so the event handler can decide whether to continue executing or terminate. For more information about handling events, see Handling and Raising Events.

When the user presses either Ctrl+C or Ctrl+Break, the CancelKeyPress event is fired and the application's ConsoleCancelEventHandler event handler is executed. The event handler is passed a ConsoleCancelEventArgs object that has two useful properties:

  • SpecialKey, which allows you to determine whether the handler was invoked as a result of the user pressing Ctrl+C (the property value is ConsoleSpecialKey.ControlC) or Ctrl+Break (the property value is ConsoleSpecialKey.ControlBreak).

  • Cancel, which allows you to determine how to your application should respond to the user pressing Ctrl+C or Ctrl+Break. By default, the Cancel property is false, which causes program execution to terminate when the event handler exits. Changing its property to true specifies that the application should continue to execute.

TipTip

If your application has simple requirements, you can use the TreatControlCAsInput property instead of this event. By setting this property to false, you can ensure that your application always exits if the user presses Ctrl+C. By setting it to true, you can ensure that pressing Ctrl+C will not terminate the application.

The event handler for this event is executed on a thread pool thread.

The following example demonstrates how the CancelKeyPress event is used. When you press Ctrl+C, the read operation is interrupted and the myHandler event handler is invoked. Upon entry to the event handler, the ConsoleCancelEventArgs.Cancel property is false, which means that the current process will terminate when the event handler terminates. However, the event handler sets the ConsoleCancelEventArgs.Cancel property to true, which means that the process will not terminate and the read operation will resume.

using System;

class Sample 
{
    public static void Main()
    {
        ConsoleKeyInfo cki;

        Console.Clear();

        // Establish an event handler to process key press events.
        Console.CancelKeyPress += new ConsoleCancelEventHandler(myHandler);
        while (true) {
            Console.Write("Press any key, or 'X' to quit, or ");
            Console.WriteLine("CTRL+C to interrupt the read operation:");

            // Start a console read operation. Do not display the input.
            cki = Console.ReadKey(true);

            // Announce the name of the key that was pressed .
            Console.WriteLine("  Key pressed: {0}\n", cki.Key);

            // Exit if the user pressed the 'X' key. 
            if (cki.Key == ConsoleKey.X) break;
        }
    }

    protected static void myHandler(object sender, ConsoleCancelEventArgs args)
    {
        Console.WriteLine("\nThe read operation has been interrupted.");

        Console.WriteLine("  Key pressed: {0}", args.SpecialKey);

        Console.WriteLine("  Cancel property: {0}", args.Cancel);

        // Set the Cancel property to true to prevent the process from terminating.
        Console.WriteLine("Setting the Cancel property to true...");
        args.Cancel = true;

        // Announce the new value of the Cancel property.
        Console.WriteLine("  Cancel property: {0}", args.Cancel);
        Console.WriteLine("The read operation will resume...\n");
    }
}
// The example displays output similar to the follwoing: 
//    Press any key, or 'X' to quit, or CTRL+C to interrupt the read operation: 
//      Key pressed: J 
//     
//    Press any key, or 'X' to quit, or CTRL+C to interrupt the read operation: 
//      Key pressed: Enter 
//     
//    Press any key, or 'X' to quit, or CTRL+C to interrupt the read operation: 
//     
//    The read operation has been interrupted. 
//      Key pressed: ControlC 
//      Cancel property: False 
//    Setting the Cancel property to true... 
//      Cancel property: True 
//    The read operation will resume... 
//     
//      Key pressed: Q 
//     
//    Press any key, or 'X' to quit, or CTRL+C to interrupt the read operation: 
//      Key pressed: X

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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