XL97: Value Returned by VarType for Omitted Arguments Differs

• Microsoft Excel 97 for Windows

SYMPTOMS

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.

CAUSE

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.

RESOLUTION

Microsoft provides examples of Visual Basic for Applications 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. The Visual Basic procedures in this article are provided 'as is' and Microsoft does not guarantee that they can be used in all situations. While Microsoft support engineers can help explain the functionality of a particular macro, they will not modify these examples to provide added functionality, nor will they help you construct macros to meet your specific needs. If you have limited programming experience, you may want to consult one of the Microsoft Solution Providers. Solution Providers offer a wide range of fee-based services, including creating custom macros. For more information about Microsoft Solution Providers, call Microsoft Customer Information Service at (800) 426-9400.

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

   If VarType(X) = 10 Then

   If (VarType(X) = 10 And Application.Version < 8) Or (VarType(X) = 1 _
       And Application.Version = 8) Then

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

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

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.

                     VarType Value for
   Microsoft Excel   Missing Arguments   Corresponds to
   -------------------------------------------------------------------
   97                 1 (vbNull)         IsNull(<variable>) = True
                                         IsMissing(<variable>) = False

   5.0, 7.0          10 (vbError)        IsMissing(<variable>) = True
                                         IsNull(<variable>) = False

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.

   Cell  Microsoft Excel 97         Microsoft Excel 5.0, 7.0   Different
   ---------------------------------------------------------------------
   A1    IsMissing = False, False   IsMissing = False, False   No
         IsNull = False, False      IsNull = False, False      No
         VarType = 5, 5             VarType = 5, 5             No

   A2    IsMissing = False, False   IsMissing = True, False    Yes
         IsNull = True, False       IsNull = False, False      Yes
         VarType = 1, 5             VarType = 10, 5            Yes

   A3    IsMissing = False, False   IsMissing = False, True    Yes
         IsNull = False, True       IsNull = False, False      Yes
         VarType = 5, 1             VarType = 5, 10            Yes

   A4    IsMissing = False, False   IsMissing = True, True     Yes
         IsNull = True, True        IsNull = False, False      Yes
         VarType = 1, 1             VarType = 10, 10           Yes

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.