XL97: Value Returned by VarType for Omitted Arguments Differs

   If VarType(X) = 10 Then
				

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

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
				

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.

  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
				

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.