HOWTO: Use Optional Arguments in Intrinsic Data Types

ID: Q163229

The information in this article applies to:

Microsoft Visual Basic Professional and Enterprise Editions for Windows, versions 5.0, 6.0

SUMMARY

One of the new features of Microsoft Visual Basic 5.0 and VBA 5.0 is the ability to define Optional arguments for data types other than Variant. These optional arguments are used in procedures.

MORE INFORMATION

Microsoft Visual Basic and VBA 5.0 allows optional arguments for the following data types:

   Data type
   ---------
   Currency
   Double
   Integer
   Long
   Single
   String
   Object

The following conditions and notes should be considered:

1. The Optional argument must be capable of being assigned a default value.

   When a procedure that has Optional arguments is called, Microsoft Visual
   Basic 5.0 assigns all arguments that were not included with a default
   value. Thus, an Optional array is not possible.

2. Optional arguments of user-defined data types are not supported.

   Microsoft Visual Basic 5.0 only supports Optional arguments of intrinsic
   data types.

3. Optional arguments that are of intrinsic data types always return False

   when used with the IsMissing function. This occurs because the IsMissing
   function is explicitly designed for un-initialized Variant data types.
   Because an intrinsic Optional argument always gets its default value if
   not passed to the procedure, it is never missing.

4. Applications written with earlier versions of Visual Basic for

   Applications will ignore the Optional modifier, and thus require the
   argument(s). A good example of this is Microsoft Access for Windows 95.

REFERENCES

Microsoft Visual Basic Online Help

Additional query words: simple data types nonvariant kbVBA500 kbVBp500 kbVBp600 kbVBp kbdsd kbDSupport kbVBA

Platform          : WINDOWS
Issue type        : kbhowto

Last Reviewed: October 15, 1998