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Information.IsNothing Method

Returns a Boolean value indicating whether an expression has no object assigned to it.

Namespace:  Microsoft.VisualBasic
Assembly:  Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)

public static bool IsNothing(
	Object Expression
)

Parameters

Expression
Type: System.Object
Required. Object expression.

Return Value

Type: System.Boolean
Returns a Boolean value indicating whether an expression has no object assigned to it.

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)


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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