Only allow numeric values in the textbox

Question

I want to make a TextBox control that only accepts numerical values.

How can I do this in VB6?

Answer 1

I let the API do it for me. I add this function to a .bas module and call it for any edit control that I need to set to numeric only.

Option Explicit

Private Const ES_NUMBER = &H2000&
Private Const GWL_STYLE = (-16)
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long


'set an editbox to numeric only - return the previous
'style on success or zero on error
Public Function ForceNumeric(ByVal EditControlhWnd As Long) As Long
    Dim lngCurStyle As Long
    Dim lngReturn As Long

    lngCurStyle = GetWindowLong(EditControlhWnd, GWL_STYLE)
    If lngCurStyle <> 0 Then
        lngReturn = SetWindowLong(EditControlhWnd, GWL_STYLE, lngCurStyle Or ES_NUMBER)
    End If

    ForceNumeric = lngReturn

End Function

To use it call the function with the handle of the TextBox.

Private Sub Form_Load()
    Dim lngResult As Long

    lngResult = ForceNumeric(Text1.hwnd)

End Sub