Visual Basic 2005 in a Nutshell, Third Edition

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Chapter 12: The Language Reference

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

TypeOf Operator

Syntax

Dim result As Boolean = TypeOf varName Is typeName

or:

Dim result As Boolean = TypeOf varName IsNot typeName

varName (required; any)

The variable, instance, or expression to compare with a data type

typeName (required)

The class, interface, structure, or other type name against which to compare

varName

Description

The TypeOf operator indicates whether an instance of data is of a specific type (True)or

not (

False). It is always used with the Is or IsNot keyword, followed by a valid .NET

type. It is most often used with

If...Then...Else statements, as in:

If (TypeOf someVariable Is Integer) Then

' ----- Integer-specific code here.

End If

New in 2005. Visual Basic 2005 introduced a new IsNot keyword that negates the

Boolean result of the

TypeOf operator.

If (TypeOf someVariable IsNot Integer) Then

' ----- Non-Integer-specific code here.

End If

Before 2005, the equivalent of this syntax required the use of the Not operator.

If Not (TypeOf someVariable Is Integer) Then

' ----- Non-Integer-specific code here.

End If

Version Differences

Visual Basic 2005 includes a new IsNot keyword. It was not available in earlier

versions of VB for .NET or in VB 6.

See Also

Is Operator, IsNot Operator

UBound Function

Class

VisualBasic.Information

Syntax

Dim result ...