Nullable types were a welcome addition to Visual Basic 2008. In Visual Basic 2010 you can use them as parameters. Here are two examples:
' Assign Nothing as the default value for nullable optional parameter.
Sub Add(ByVal x As Integer, ByVal y As Integer, Optional ByVal z As Integer? = Nothing)
' code removed for brevity
End Sub
' Assign an integer value to a nullable optional paramter of type Double.
Sub Process(ByVal x As Integer, ByVal y As Integer, Optional ByVal z As Double? = 4)
' code removed for brevity
End Sub
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