Public Shared Function IsDigitOnly (ByVal varStr As String) As Boolean
Dim bRet As Boolean = False
If (varStr.Length = 0) Then Return bRet
bRet = True
For( i As Integer = 0 To varStr.Length -1 )
if (Not IsDigit(varStr(i))) Then
bRet = False
Exit For
End If
Next
Return bRet
End Function