XL97: Value Returned by VarType for Omitted Arguments Differs

When you call a custom Visual Basic for Applications function from a formula in a cell in a Microsoft Excel 97 worksheet, the VarType function may return different values for missing optional arguments than it does in earlier versions of Microsoft Excel. The IsMissing and IsNull functions may also return different results.

This problem occurs because the method Microsoft Excel 97 uses to send argument from worksheet formulas to Visual Basic for Applications functions is different from the method used by earlier versions of Microsoft Excel.

NOTE: This problem does not occur when you use a Visual Basic for Applications subroutine to call a Visual Basic for Applications 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 a Microsoft Certified Partner or Microsoft Advisory Services. For more information, visit these Microsoft Web sites:

Microsoft Certified Partners - https://partner.microsoft.com/global/30000104 (https://partner.microsoft.com/global/30000104)

Microsoft Advisory Services - http://support.microsoft.com/gp/advisoryservice (http://support.microsoft.com/gp/advisoryservice)

For more information about the support options that are available and about how to contact Microsoft, visit the following Microsoft Web site:http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS (http://support.microsoft.com/default.aspx?scid=fh;en-us;cntactms) If the function uses the VarType, IsMissing, and/or IsNull functions to check the status of a missing argument, it may be necessary to modify the function to accommodate the change in behavior in Microsoft Excel 97.

For example, if your function contains a line of code that is similar to the following change the line so that it accounts for a VarType of 1 (the default) in Microsoft Excel 97, for example: This line of code accounts for the difference in behavior between Microsoft Excel 97 and earlier versions of Microsoft Excel.

You can use similar methods to correct any lines of code that uses the IsMissing and/or IsNull functions.

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem no longer occurs in Microsoft Excel 2000.

When you call a custom function from a formula in a worksheet cell, the value that is returned by VarType for missing optional arguments differs according to the version of Microsoft Excel that you are using. The values that are returned by VarType for different versions of Microsoft Excel are listed in the following table. NOTE: This difference does NOT apply when you use a Visual Basic for Applications subroutine to call a custom function. If you omit arguments when you use a Visual Basic for Applications subroutine to call a custom function, the value that is returned by VarType for the missing arguments is 10 in all versions of Microsoft Excel (versions 5.0, 7.0, and Microsoft Excel 97).

The following example demonstrates the change in behavior for the VarType function:

1. Type the following Visual Basic for Applications code into a Visual Basic module in Microsoft Excel:

          Function TestIsMissing(Optional A, Optional B)
             TestIsMissing = "IsMissing = " & IsMissing(A) & ", " & _
                 IsMissing(B) & Chr(10) & "IsNull = " & IsNull(A) & ", " & _
                 IsNull(B) & Chr(10) & "VarType = " & VarType(A) & ", " & _
                 VarType(B)
         End Function
   
         Sub TestProc()
             MsgBox TestIsMissing(A:=1, B:=2)
             MsgBox TestIsMissing(B:=2)
             MsgBox TestIsMissing(A:=1)
             MsgBox TestIsMissing
         End Sub
   						

2. In a worksheet in the same workbook, select cells A1:A4.
3. On the Format menu, click Cells. Then, click the Alignment tab. Click to select the Wrap Text check box. Then, click OK.
4. On the Format menu, point to Column and click Width. Type 25, and then click OK.
5. Type the following formulas:
   A1: =TestIsMissing(1,2)
   A2: =TestIsMissing(,2)
   A3: =TestIsMissing(1,)
   A4: =TestIsMissing(,)
   Note that each formula uses a different set of arguments. Some of the arguments are not used in this example.

Depending on the version of Microsoft Excel you are using, the results that are returned by the formulas are different. The results that are returned are listed in the following table. Microsoft Excel 97 reports missing arguments as null values because the value that is returned by VarType for these arguments is 1. In earlier versions of Microsoft Excel, the missing arguments are reported as error values because the value that is returned by VarType is 10.

If you run the TestProc macro, the four message boxes that appear are identical in all versions of Microsoft Excel (5.0, 7.0, and Microsoft Excel 97). If you omit arguments when you call a Visual Basic for Applications function from a macro, the value returned by VarType for the missing arguments is always 10.