ConsoleCancelEventArgs.Cancel 属性

定义

命名空间:

System

程序集:

System.Console.dll

Source:

ConsoleCancelEventArgs.cs

获取或设置一个值，该值指示同时按下 Control 修改键和 C 控制台键 (Ctrl+C) 或 Ctrl+Break 键是否会终止当前进程。 默认值为 false，这将终止当前进程。

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

属性值

Boolean

如果当前进程在事件处理程序结束时应继续，则为 true；如果当前进程应终止，则为 false。 默认值为 false；当前进程将在事件处理程序返回时终止。 如果为 true，当前进程将继续。

示例

以下示例演示如何使用 Cancel 属性来处理事件。

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

注解

调用 Cancel 事件的处理程序时，属性会自动初始化 false 为 CancelKeyPress 。 Cancel事件处理程序完成时的 属性值确定当前进程是恢复还是终止。

在按下 Ctrl+C 后的设置操作中，指定 true 以指示当前进程应在事件处理程序结束时恢复，或 false 指定当前进程应终止。

调用方说明

在 .NET Framework 3.5 和 .NET Framework 4 中，如果用户CancelKeyPress按 Ctrl+Break InvalidOperationException 调用了事件，则尝试将 属性true设置为 Cancel 。 在 .NET Framework 4.5 中，可以在用户按 Ctrl+Break 并取消应用程序终止后将 属性设置为 Canceltrue 。

另请参阅

• ConsoleCancelEventHandler
• ConsoleKey
• ConsoleModifiers
• SpecialKey