CancelEventArgs Class

Provides data for a cancelable event.

System.Object
  System.EventArgs
    System.ComponentModel.CancelEventArgs

Namespace:  System.ComponentModel
Assemblies:   System.ComponentModel (in System.ComponentModel.dll)
  System (in System.dll)

'Declaration
Public Class CancelEventArgs _
	Inherits EventArgs

The CancelEventArgs type exposes the following members.

  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCancelEventArgsInitializes a new instance of the CancelEventArgs class with the Cancel property set to false.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCancelEventArgs(Boolean)Initializes a new instance of the CancelEventArgs class with the Cancel property set to the given value.
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  NameDescription
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCancelGets or sets a value indicating whether the event should be canceled.
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  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsToStringReturns a string that represents the current object. (Inherited from Object.)
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A cancelable event is raised by a component when it is about to perform an action that can be canceled, such as the Closing event of a Form.

NoteNote

The Closing event is deprecated and has been replaced by FormClosing. It is offered as an example here only to illustrate the usage of CancelEventArgs.

CancelEventArgs provides the Cancel property to indicate whether the event should be canceled.

The following example uses CancelEventArgs and a CancelEventHandler to handle the Closing event of a Form. This code assumes that you have created a Form with a class-level Boolean variable named isDataSaved. It also assumes that you have added a statement to invoke the OtherInitialize method from the form's Load method or the constructor (after the call to InitializeComponent).

' Call this method from the Load method of your form. 
Private Sub OtherInitialize()
    ' Exchange commented line and note the difference. 
    Me.isDataSaved = True 
    'Me.isDataSaved = False 
End Sub 'OtherInitialize

Private Sub Form1_Closing(sender As Object, e As _
   System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
    If Not isDataSaved Then
        e.Cancel = True
        MessageBox.Show("You must save first.")
    Else
        e.Cancel = False
        MessageBox.Show("Goodbye.")
    End If 
End Sub 'Form1_Closing

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, 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.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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