Knowledge Base

PRB: Variable Not Defined Error Message When Using a Constant

Article ID: 179027

Article Last Modified on 2/12/2007

APPLIES TO

This article was previously published under Q179027

SYMPTOMS

The following error message displays when you attempt to use a predefined constant for an automation server:
"Compile Error:
Variable Not Defined"
For example, you may receive this error when you try to use the constant xlR1C1 from the Microsoft Excel Object Library.

CAUSE

You are using late binding on an ActiveX component.

RESOLUTION

You can use early binding by referencing the object library for the automation server in your project. Click References on the Project menu to select the object library.

or-

If you want to use late binding, declare your own constant and assign it to the numeric value of the predefined constant. For example, the constant xlR1C1 is equivalent to -4150. Therefore, you could add the following to your project.

Const xlR1C1 = -4150

STATUS

This behavior is by design.

MORE INFORMATION

Late binding occurs when you declare a variable As Object, As Form, As Control, or As Variant and Visual Basic cannot determine at compile time what sort of object reference the variable will contain. Therefore, Visual Basic must use late binding to determine at run time whether the actual object has the properties and methods you call using the variable.

Early binding occurs when you make a reference to the object library at design time. Visual Basic then knows what object library contains the properties and methods when you make your variable call. Early binding also provides some performance gains.

REFERENCES

"How Binding Affects ActiveX Component Performance" in the Visual Basic Component Tools Guide, version 5.0.

Keywords: kberrmsg kbinterop kbautomation kbprb KB179027


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