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Nothing and Strings in Visual Basic

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The Visual Basic runtime and the .NET Framework evaluate Nothing differently when it comes to strings.

Visual Basic Runtime and the .NET Framework

Consider the following example:

    Dim MyString As String = "This is my string"
    Dim stringLength As Integer

    ' Explicitly set the string to Nothing.
    MyString = Nothing

    ' stringLength = 0
    stringLength = Len(MyString)

    ' This line, however, causes an exception to be thrown.
    stringLength = MyString.Length

The Visual Basic runtime usually evaluates Nothing as an empty string (""). The .NET Framework does not, however, and throws an exception whenever an attempt is made to perform a string operation on Nothing.

See also