ConsoleCancelEventArgs.Cancel Property
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public:
property bool Cancel { bool get(); void set(bool value); };
public bool Cancel { get; set; }
member this.Cancel : bool with get, set
Public Property Cancel As Boolean
true
if the current process should resume when the event handler concludes; false
if the current process should terminate. The default value is false
; the current process terminates when the event handler returns. If true
, the current process continues.
The following example demonstrates how to use the Cancel property to handle an event.
using namespace System;
void OnCancelKeyPressed(Object^ sender,
ConsoleCancelEventArgs^ args)
{
Console::WriteLine("{0}The read operation has been interrupted.",
Environment::NewLine);
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...{0}",
Environment::NewLine);
}
int main()
{
// Clear the screen.
Console::Clear();
// Establish an event handler to process key press events.
Console::CancelKeyPress +=
gcnew ConsoleCancelEventHandler(OnCancelKeyPressed);
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.
ConsoleKeyInfo^ keyInfo = Console::ReadKey(true);
// Announce the name of the key that was pressed .
Console::WriteLine(" Key pressed: {0}{1}", keyInfo->Key,
Environment::NewLine);
// Exit if the user pressed the 'X' key.
if (keyInfo->Key == ConsoleKey::X)
{
break;
}
}
}
// The example displays output similar to the following:
// 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
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($" Key pressed: {cki.Key}\n");
// Exit if the user pressed the 'X' key.
if (cki.Key == ConsoleKey.X) break;
}
}
protected static void myHandler(object sender, ConsoleCancelEventArgs args)
{
Console.WriteLine("\nThe read operation has been interrupted.");
Console.WriteLine($" Key pressed: {args.SpecialKey}");
Console.WriteLine($" Cancel property: {args.Cancel}");
// Set the Cancel property to true to prevent the process from terminating.
Console.WriteLine("Setting the Cancel property to true...");
args.Cancel = true;
// Announce the new value of the Cancel property.
Console.WriteLine($" Cancel property: {args.Cancel}");
Console.WriteLine("The read operation will resume...\n");
}
}
// The example displays output similar to the following:
// 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
open System
let myHandler sender (args: ConsoleCancelEventArgs) =
printfn "\nThe read operation has been interrupted."
printfn $" Key pressed: {args.SpecialKey}"
printfn $" Cancel property: {args.Cancel}"
// Set the Cancel property to true to prevent the process from terminating.
printfn "Setting the Cancel property to true..."
args.Cancel <- true
// Announce the new value of the Cancel property.
printfn $" Cancel property: {args.Cancel}"
printfn "The read operation will resume...\n"
// Establish an event handler to process key press events.
Console.CancelKeyPress.AddHandler(ConsoleCancelEventHandler myHandler)
let mutable quit = false
while not quit do
printf "Press any key, or 'X' to quit, or "
printfn "CTRL+C to interrupt the read operation:"
// Start a console read operation. Do not display the input.
let cki = Console.ReadKey true
// Announce the name of the key that was pressed .
printfn $" Key pressed: {cki.Key}\n"
// Exit if the user pressed the 'X' key.
if cki.Key = ConsoleKey.X then
quit <- true
// The example displays output similar to the following:
// Press any key, or 'X' to quit, or CTRL+C to interrupt the read operation:
// Key pressed: J
//
// Press any key, or 'X' to quit, or CTRL+C to interrupt the read operation:
// Key pressed: Enter
//
// Press any key, or 'X' to quit, or CTRL+C to interrupt the read operation:
//
// The read operation has been interrupted.
// Key pressed: ControlC
// Cancel property: False
// Setting the Cancel property to true...
// Cancel property: True
// The read operation will resume...
//
// Key pressed: Q
//
// Press any key, or 'X' to quit, or CTRL+C to interrupt the read operation:
// Key pressed: X
Class Sample
Public Shared Sub Main()
Dim cki As ConsoleKeyInfo
Console.Clear()
' Establish an event handler to process key press events.
AddHandler Console.CancelKeyPress, AddressOf myHandler
While True
Console.Write("Press any key, or 'X' to quit, or ")
Console.WriteLine("CTRL+C to interrupt the read operation:")
' Start a console read operation. Do not display the input.
cki = Console.ReadKey(True)
' Announce the name of the key that was pressed .
Console.WriteLine($" Key pressed: {cki.Key}{vbCrLf}")
' Exit if the user pressed the 'X' key.
If cki.Key = ConsoleKey.X Then Exit While
End While
End Sub
Protected Shared Sub myHandler(ByVal sender As Object, _
ByVal args As ConsoleCancelEventArgs)
Console.WriteLine($"{vbCrLf}The read operation has been interrupted.")
Console.WriteLine($" Key pressed: {args.SpecialKey}")
Console.WriteLine($" Cancel property: {args.Cancel}")
' Set the Cancel property to true to prevent the process from terminating.
Console.WriteLine("Setting the Cancel property to true...")
args.Cancel = True
' Announce the new value of the Cancel property.
Console.WriteLine($" Cancel property: {args.Cancel}")
Console.WriteLine($"The read operation will resume...{vbCrLf}")
End Sub
End Class
' The example diplays output similar to the following:
' 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
The Cancel property is automatically initialized to false
when the handler for the CancelKeyPress event is invoked. The value of the Cancel property when the event handler finishes determines whether the current process resumes or terminates.
In a set operation after Ctrl+C is pressed, specify true
to indicate that the current process should resume when the event handler concludes, or false
to indicate that the current process should terminate.
In the .NET Framework 3.5 and .NET Framework 4, attempting to set the Cancel property to true
if the CancelKeyPress event was invoked by the user pressing Ctrl+Break threw an InvalidOperationException exception. In the .NET Framework 4.5, you can set the Cancel property to true
after the user presses Ctrl+Break and cancel the termination of the application.
מוצר | גירסאות |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.3, 1.4, 1.6, 2.0, 2.1 |
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