Occurs when the control is finished validating.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
When you change the focus by using the keyboard (TAB, SHIFT+TAB, and so on), by calling the Select or SelectNextControl methods, or by setting the ContainerControl.ActiveControl property to the current form, focus events occur in the following order:
When you change the focus by using the mouse or by calling the Focus method, focus events occur in the following order:
Do not attempt to set focus from within the Enter, GotFocus, Leave, LostFocus, Validating, or event handlers. Doing so can cause your application or the operating system to stop responding. For more information, see the WM_KILLFOCUS topic, and the "Message Deadlocks" section of the About Messages and Message Queues topic.
For more information about handling events, see Handling and Raising Events.
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. This example requires that a TextBox and ErrorProvider control have been created on a form.
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 'firstname.lastname@example.org' " 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