Returns a Boolean value indicating whether an expression has no object assigned to it.
Assembly: Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)
IsNothing returns True if the expression represents an object variable that currently has no object assigned to it; otherwise, it returns False.
IsNothing is intended to work on reference types. A value type cannot hold a value of Nothing and reverts to its default value if you assign Nothing to it. If you supply a value type in Expression, IsNothing always returns False.
The following example uses the IsNothing function to determine if an object variable is associated with any object instance.
Dim testVar As Object ' No instance has been assigned to variable testVar yet. Dim testCheck As Boolean ' The following call returns True. testCheck = IsNothing(testVar) ' Assign a string instance to variable testVar. testVar = "ABCDEF" ' The following call returns False. testCheck = IsNothing(testVar) ' Disassociate variable testVar from any instance. testVar = Nothing ' The following call returns True. testCheck = IsNothing(testVar)
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.