CancelEventArgs.Cancel Property

Gets or sets a value indicating whether the event should be canceled.

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

'Declaration
Public Property Cancel As Boolean

Property Value

Type: System.Boolean
true if the event should be canceled; otherwise, false.

The following example uses CancelEventArgs and a CancelEventHandler to handle the FormClosing 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: 4.5, 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

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, 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.

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