Nothing and Strings in Visual Basic

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

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.

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