ID: Q141288
The information in this article applies to:
In Microsoft Excel, you can create custom Microsoft Visual Basic for Applications functions to perform calculations. By default, these custom functions are available to all worksheets in the workbook that contains the custom function. Therefore, you can call them just as you call built-in functions in Microsoft Excel. However, if you attempt to call a custom function from outside of the workbook that contains the code, you must first make a reference to the workbook that contains the custom function.
Microsoft provides programming examples 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 article assumes that you are familiar with the programming language being demonstrated and the tools used to create and debug procedures. Microsoft support professionals can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific needs. If you have limited programming experience, you may want to contact the Microsoft fee-based consulting line at (800) 936-5200. For more information about the support options available from Microsoft, please see the following page on the World Wide Web:
http://www.microsoft.com/support/supportnet/refguide/
1. Open a new workbook.
2. Insert a module sheet using the appropriate method for your version of
Excel.
Excel 98 Macintosh Edition
--------------------------
a. Start the Visual Basic Editor (press OPTION+F11).
b. On the Insert menu, click Module.
Excel 97 for Windows
---------------------
a. Start the Visual Basic Editor (press ALT+F11).
b. On the Insert menu, click Module.
Excel versions 5.0, 7.0 for Windows, version 5.0 for Macintosh
--------------------------------------------------------------
On the Insert menu, point to Macro, and then click Module.
Function myfunction(x)
myfunction = x * 2
End Function
To call this function from within Test.xls, type the following formula in cell A1 on Sheet1:
=myfunction(3)
In order to call the function from a workbook, you must create a reference to the workbook that contains the code. To create a reference, follow these steps:
1. Open another new workbook.
2. Save this workbook as Test2.xls.
3. Insert a module sheet using the appropriate method for your version of
Excel.
Excel 98 Macintosh Edition
--------------------------
a. Start the Visual Basic Editor (press OPTION+F11).
b. On the Insert menu, click Module.
Excel 97 for Windows
--------------------
a. Start the Visual Basic Editor (press ALT+F11).
b. On the Insert menu, click Module.
Excel Versions 5.0, 7.0 for Windows, Version 5.0 for Macintosh
--------------------------------------------------------------
On the Insert menu, point to Macro, and then click Module.
version of Excel.
Excel 98 Macintosh Edition
--------------------------
a. Press COMMAND+R to activate the Project Explorer window.
b. Select "VBAProject (Test.xls)," and then click VBAProject Properties
on the View menu.
c. In the Project Name box, type "MyProject" (without the quotation
marks), and then click OK.
d. Select "VBAProject (Test2.xls)" in the Project Explorer window.
e. On the Tools menu, click References. Click Myfunction, and then
click OK.
Excel 97 for Windows
--------------------
a. Press CTRL+R to activate the Project Explorer window.
b. Select "VBAProject (Test.xls)," and then click VBAProject Properties
on the View menu.
c. In the Project Name box, type "MyProject" (without the quotation
marks), and then click OK.
d. Select "VBAProject (Test2.xls)" in the Project Explorer window.
e. On the Tools menu, click References. Click Myfunction, and then
click OK.
Excel versions 5.0, 7.0 for Windows, version 5.0 for Macintosh
--------------------------------------------------------------
On the Tools menu, click References. Click Test.xls, and then click OK.
=myfunction(5)
NOTE: If the reference is not made as outlined in steps 1-4, cell A1 will display the #NAME? error value because Microsoft Excel does not know where to find the "myfunction" custom function. Naming the function and the project with the same name will also result in the #NAME? error. Note also that you cannot create a reference to an unsaved workbook, so if you encounter an error when you try to create the reference, make sure the workbook that contains the custom function has been saved.
For more information about Custom Functions, from the Visual Basic Editor, click Contents And Index on the Help menu, click the Index tab in Help, type the following text
Function procedures
For more information about topic, from the Visual Basic Editor, click the Office Assistant, type "function," click Search, and then click to view "Writing a Function Procedure."
NOTE: If the Assistant is hidden, click the Office Assistant button on the Standard toolbar. If the Assistant is not able to answer your query, please see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q176476
TITLE : OFF: Office Assistant Not Answering Visual Basic Questions
For more information about Custom Functions, click Answer Wizard on the Help menu and type:
tell me how to create a user-defined function
Keywords : kbprg kbdta kbdtacode PgmHowto KbVBA
Version : WINDOWS:5.0,5.0c,7.0,97; MACINTOSH:5.0,5.0a,98
Platform : MACINTOSH WINDOWS
Issue type : kbhowtoLast Reviewed: May 17, 1999