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Control.CausesValidation Property

Gets or sets a value indicating whether the control causes validation to be performed on any controls that require validation when it receives focus.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

'Declaration
Public Property CausesValidation As Boolean
'Usage
Dim instance As Control 
Dim value As Boolean 

value = instance.CausesValidation

instance.CausesValidation = value

Property Value

Type: System.Boolean
true if the control causes validation to be performed on any controls requiring validation when it receives focus; otherwise, false. The default is true.

If the CausesValidation property is set to false, the Validating and Validated events are suppressed.

The CausesValidation property value is typically set to false for controls such as a Help button.

The following code example uses the derived class TextBox and validates an e-mail address that the user enters. If the e-mail address is not in the standard format (containing "@" and "."), the validation fails, an ErrorProvider icon is displayed, and the event is canceled. One of the buttons on the form has its CausesValidation property set to false. Clicking or setting focus to this button does not trigger validation. This example requires that a TextBox, an ErrorProvider control, and a Button have been created on a form.

    Public Sub New()
        MyBase.New()

        InitializeComponent()
        'Set button2 to be non-validating. 
        Me.button2.CausesValidation = False 
    End Sub 

   Private Function ValidEmailAddress(ByVal emailAddress As String, ByRef errorMessage As String) As Boolean 
      ' Confirm there is text in the control. 
      If textBox1.Text.Length = 0 Then
         errorMessage = "E-mail address is required." 
         Return False 

      End If 

      ' Confirm that there is an "@" and a "." in the e-mail address, and in the correct order. 
      If emailAddress.IndexOf("@") > -1 Then 
         If (emailAddress.IndexOf(".", emailAddress.IndexOf("@")) > emailAddress.IndexOf("@")) Then
            errorMessage = "" 
            Return True 
         End If 
      End If

      errorMessage = "E-mail address must be valid e-mail address format." + ControlChars.Cr + _
        "For example 'someone@example.com' " 
      Return False 
End Function 

   Private Sub textBox1_Validating(ByVal sender As Object, _
   ByVal e As System.ComponentModel.CancelEventArgs) Handles textBox1.Validating

      Dim errorMsg As String 
      If Not ValidEmailAddress(textBox1.Text, errorMsg) Then 
         ' Cancel the event and select the text to be corrected by the user.
         e.Cancel = True
         textBox1.Select(0, textBox1.Text.Length)

         ' Set the ErrorProvider error with the text to display.  
         Me.errorProvider1.SetError(textBox1, errorMsg)
      End If 
   End Sub 


   Private Sub textBox1_Validated(ByVal sender As Object, _
   ByVal e As System.EventArgs) Handles textBox1.Validated
      ' If all conditions have been met, clear the error provider of errors.
      errorProvider1.SetError(textBox1, "")
   End Sub

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
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