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ConsoleCancelEventHandler Delegate

Note: This delegate is new in the .NET Framework version 2.0.

Represents the method that will handle the CancelKeyPress event of a System.Console.

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

public delegate void ConsoleCancelEventHandler (
	Object sender,
	ConsoleCancelEventArgs e
)
/** @delegate */
public delegate void ConsoleCancelEventHandler (
	Object sender, 
	ConsoleCancelEventArgs e
)
JScript supports the use of delegates, but not the declaration of new ones.

Parameters

sender

The source of the event.

e

A System.ConsoleCancelEventArgs object that contains the event data.

When you create a ConsoleCancelEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.

The following code example demonstrates how to use the ConsoleCancelEventHandler class to handle an event.

// This example demonstrates:
// the Console.CancelKeyPress event,
// the ConsoleCancelEventHandler delegate, 
// the ConsoleCancelEventArgs.SpecialKey property, and 
// the ConsoleCancelEventArgs.Cancel property.

using System;

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

// Clear the screen.
    Console.Clear();

// Turn off the default system behavior when CTRL+C is pressed. When 
// Console.TreatControlCAsInput is false, CTRL+C is treated as an
// interrupt instead of as input.
    Console.TreatControlCAsInput = false;

// Establish an event handler to process key press events.
    Console.CancelKeyPress += new ConsoleCancelEventHandler(myHandler);
    while (true)
        {
// Prompt the user.
        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;
        }
    }

/*
   When you press CTRL+C, the read operation is interrupted and the 
   console cancel event handler, myHandler, is invoked. Upon entry 
   to the event handler, the Cancel property is false, which means 
   the current process will terminate when the event handler terminates. 
   However, the event handler sets the Cancel property to true, which 
   means the process will not terminate and the read operation will resume.
*/
    protected static void myHandler(object sender, ConsoleCancelEventArgs args)
    {
// Announce that the event handler has been invoked.
    Console.WriteLine("\nThe read operation has been interrupted.");

// Announce which key combination was pressed.
    Console.WriteLine("  Key pressed: {0}", args.SpecialKey);

// Announce the initial value of the Cancel property.
    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");
    }
}
/*
This code example produces results similar to the following text:

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

*/

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0
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