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Control.OnKeyPress Method

Raises the KeyPress event.

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

Protected Overridable Sub OnKeyPress ( _
	e As KeyPressEventArgs _
Dim e As KeyPressEventArgs 



Type: System.Windows.Forms.KeyPressEventArgs

A KeyPressEventArgs that contains the event data.

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

The OnKeyPress method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors:

When overriding OnKeyPress in a derived class, be sure to call the base class's OnKeyPress method so that registered delegates receive the event.

The following code example uses the KeyPress event to prevent characters from entering the control.

' Boolean flag used to determine when a character other than a number is entered. 
Private nonNumberEntered As Boolean = False 

' Handle the KeyDown event to determine the type of character entered into the control. 
Private Sub textBox1_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) _
     Handles textBox1.KeyDown
    ' Initialize the flag to false.
    nonNumberEntered = False 

    ' Determine whether the keystroke is a number from the top of the keyboard. 
    If e.KeyCode < Keys.D0 OrElse e.KeyCode > Keys.D9 Then 
        ' Determine whether the keystroke is a number from the keypad. 
        If e.KeyCode < Keys.NumPad0 OrElse e.KeyCode > Keys.NumPad9 Then 
            ' Determine whether the keystroke is a backspace. 
            If e.KeyCode <> Keys.Back Then 
                ' A non-numerical keystroke was pressed.  
                ' Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = True 
            End If 
        End If 
    End If 
    'If shift key was pressed, it's not a number. 
    If Control.ModifierKeys = Keys.Shift Then
        nonNumberEntered = true
    End If 
End Sub 'textBox1_KeyDown

' This event occurs after the KeyDown event and can be used  
' to prevent characters from entering the control. 
Private Sub textBox1_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) _
    Handles textBox1.KeyPress
    ' Check for the flag being set in the KeyDown event. 
    If nonNumberEntered = True Then 
        ' Stop the character from being entered into the control since it is non-numerical.
        e.Handled = True 
    End If 
End Sub 'textBox1_KeyPress

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, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

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

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0