在TEXT文本框中过滤输入为数值

参数keyin为输入值，txt为检查数值字符串，editable为是否backspace是否可用,xsw 为小数的位数,position 光标位置
'调用举例
'Private Sub Text1_KeyPress(KeyAscii As Integer)
'    KeyAscii = FilterNum(KeyAscii, Text1.Text, True,2,Text1.selstart)
'End Sub

Public Function FilterNum(ByVal KeyIn As Integer, ByVal Txt As String, ByVal EditAble As Boolean, ByVal XSW As Integer, ByVal Position As Integer) As Integer
    Dim ValidateList As String
    Dim ValidateString As String
 
    Dim KeyOut As Integer
    Dim i As Integer
   
    ValidateString = "-0123456789."
 
    If EditAble = True Then
        ValidateList = UCase(ValidateString) & Chr(8)
    Else
        ValidateList = UCase(ValidateString)
    End If
   
    If InStr(1, ValidateList, UCase(Chr(KeyIn)), 1) > 0 Then
        KeyOut = KeyIn
    Else
        FilterNum = 0
        Exit Function
    End If
   
    If KeyOut = 8 Then
        FilterNum = 8
        Exit Function
    End If
   
    If (KeyOut = Asc("-")) And Not (Position = 0 And Left(Txt, 1) <> "-") Then
        FilterNum = 0
        Exit Function
    End If
   
    If XSW > 0 Then
        i = InStr(1, Txt, ".", vbTextCompare)
        If i > 0 And KeyOut = Asc(".") Then
            FilterNum = 0
            Exit Function
        End If
       
        If i > 0 And i + XSW = Len(Txt) Then
            If KeyOut <> Asc("-") Then
                FilterNum = 0
            End If
        End If
       
        If i <= 0 Then
            If Left(Txt, 1) = "-" And KeyOut = Asc(".") And Position = 1 Then
                FilterNum = 0
                Exit Function
            End If
        End If
           
    Else
        If KeyOut = Asc(".") Then
            FilterNum = 0
            Exit Function
        End If
    End If
   
    FilterNum = KeyOut
   
End Function