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Information.IsNothing Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

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

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

Syntax

'Declaration
Public Shared Function IsNothing ( _
    Expression As Object _
) As Boolean

public static bool IsNothing(
    Object Expression
)

Parameters

Return Value

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

Remarks

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.

Examples

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)

Version Information

Silverlight

Supported in: 5, 4, 3

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.