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| Title | Make a TextBox allow only letters and numbers |
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| Keywords | TextBox, letters, numbers, field, validate, context menu, popup |
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| Categories | Controls, Tips and Tricks, API |
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In the TextBox's KeyPress event, look for characters that are not letters or numbers and discard them by setting KeyAscii to 0.
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' Allow only letters and numbers.
Private Sub Text1_KeyPress(KeyAscii As Integer)
Dim ch As String
ch = Chr$(KeyAscii)
If Not ( _
(ch >= "a" And ch <= "z") Or _
(ch >= "A" And ch <= "Z") Or _
(ch >= "0" And ch <= "9") _
) Then
' Cancel the character.
KeyAscii = 0
End If
End Sub
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To prevent the user from right clicking on the TextBox and using the context menu to paste invalid characters, subclass the TextBox and discard WM_CONTEXTMENU messages.
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' Pass along all messages except the one that
' makes the context menu appear.
Public Function NoPopupWindowProc(ByVal hWnd As Long, ByVal _
Msg As Long, ByVal wParam As Long, ByVal lParam As _
Long) As Long
Const WM_NCDESTROY = &H82
Const WM_CONTEXTMENU = &H7B
' If we're being destroyed,
' restore the original WindowProc.
If Msg = WM_NCDESTROY Then
SetWindowLong _
hWnd, GWL_WNDPROC, _
OldWindowProc
End If
If Msg <> WM_CONTEXTMENU Then _
NoPopupWindowProc = CallWindowProc( _
OldWindowProc, hWnd, Msg, wParam, _
lParam)
End Function
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