cancel_key_press

event<console, console_cancel_event_handler> xtd::console::cancel_key_press

static

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).

Remarks

This event is used in conjunction with xtd::console_cancel_event_handler and xtd::console_cancel_event_args. The cancel_key_press 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 cancel_key_press event is fired and the application's console_cancel_event_handler event handler is executed. The event handler is passed a console_cancel_event_args object that has two useful properties:

• special_key, which allows you to determine whether the handler was invoked as a result of the user pressing Ctrl+C (the property value is console_special_key::control_c) or Ctrl+Break (the property value is console_special_key.control_break).
• 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.

Note

If your application has simple requirements, you can use the treat_control_c_as_input 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.

Warning

The xtd::signal::interrupt and xtd::console_special_key::control_c use the same signal (SIGINT).

The xtd::signal::interrupt and xtd::console_special_key::control_c can be cancelled with xtd::environment::cancel_signal event or xtd::console::cancel_key_press event. Both of these events are called when SIGINT is raised.