Knowledge Base

IS Operator Does Not Work with Microsoft Excel Objects

Article ID: 111493

Article Last Modified on 10/11/2006

APPLIES TO

This article was previously published under Q111493

SYMPTOMS

If you use the Is operator in a Microsoft Visual Basic Programming System, Applications Edition module to compare Microsoft Excel objects, the comparison may return the value FALSE even if you are comparing an object to itself.

CAUSE

The Is operator compares two object reference variables. However, in some cases, a different object is returned each time you use a property to return an object. For example, when you use the Selection property to return a selected Microsoft Excel object, a different object is returned by each call to the Selection property.

EXAMPLE 1

If you use the Is operator to compare the Microsoft Excel object returned by the Selection property to the same object returned by the Selection property as in the following lines of code

In a Visual Basic Module in Microsoft Excel

   If Selection Is Selection Then Beep

In a Visual Basic, Applications Edition Module

   If Application.Selection Is _
      ActiveSheet.Range(Application.Selection.Address) Then Beep
the comparison returns the value FALSE, and neither of these lines of code causes the system to beep. In this case, the object does not know that a reference has already been made to it and returns another reference.

EXAMPLE 2

The same issue occurs if you use the ActiveSheet property to return an object such as a button, check box, or group box. In the following example, the comparison also returns the value FALSE even though you are comparing a button to itself.

In a Visual Basic Module in Microsoft Excel

   If ActiveSheet.Buttons(1) Is ActiveSheet.Buttons("Button 1") _
      Then Beep
and you do not receive a beep.

WORKAROUND

To use the Is operator to compare two Microsoft Excel objects that are the same as in the above examples, use following examples:

EXAMPLE 1

In a Visual Basic Module in Microsoft Excel

   ' Use the Address method and the equal sign (=) operator to
   ' compare range references
   If Selection.Address = Selection.Address Then Beep

In a Visual Basic, Applications Edition Module

   ' Use the value of a unique property of an object for
   ' comparison as a workaround.
   If Application.Selection.Address = _
      ActiveSheet.Range(Application.Selection.Address).Address Then Beep

EXAMPLE 2

In a Visual Basic Module in Microsoft Excel

   ' Use Name method and the equal sign (=) operator to
   ' compare button objects
   If ActiveSheet.Buttons(1).Name = ActiveSheet.Buttons("Button 1").Name _
      Then Beep
Microsoft provides examples of Visual Basic procedures for illustration only, without warranty either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. This Visual Basic procedure is provided 'as is' and Microsoft does not guarantee that it can be used in all situations. Microsoft does not support modifications of this procedure to suit customer requirements for a particular purpose. Note that a line that is preceded by an apostrophe introduces a comment in the code--comments are provided to explain what the code is doing at a particular point in the procedure. Note also that an underscore character (_) indicates that code continues from one line to the next. You can type lines that contain this character as one logical line or you can divide the lines of code and include the line continuation character. For more information about Visual Basic for Applications programming style, see the "Programming Style in This Manual" section in the "Document Conventions" section of the "Visual Basic User's Guide."

REFERENCES

For more information about the Is Operator, choose the Search button in the Visual Basic Reference and type:

is

Keywords: KB111493


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