4523756273

Chapter 9: Using VBA and Worksheet Functions
More about Using Worksheet Functions
Newcomers to VBA often confuse VBA’s built-in functions and Excel’s workbook
functions. A good rule to remember is that VBA doesn’t try to reinvent
the wheel. For the most part, VBA doesn’t duplicate Excel worksheet functions.
139
For most worksheet functions that are unavailable as methods of the
WorksheetFunction object, you can use an equivalent VBA built-in operator
or function. For example, the MOD worksheet function is not available in the
WorksheetFunction object because VBA has an equivalent, its built-in Mod
operator.
Bottom line? If you need to use a function, first determine whether VBA has
something that meets your needs. If not, check out the worksheet functions. If
all else fails, you may be able to write a custom function by using VBA.
Using Custom Functions
I’ve covered VBA functions and Excel worksheet functions. The third category
of functions you can use in your VBA procedures is custom functions.
A custom function (also known as User Defined Function, UDF) is one you
develop yourself by using (what else?) VBA. To use a custom function, you
must define it in the workbook in which you use it.
Here’s an example of defining a simple Function procedure and then using it
in a VBA Sub procedure:
Function MultiplyTwo(num1, num2) As Double
MultiplyTwo = num1 * num2
End Function
Sub ShowResult()
Dim n1 As Double, n2 As Double
Dim Result As Double
n1 = 123
n2 = 544
Result = MultiplyTwo(n1, n2)
MsgBox Result
End Sub
The custom function MultiplyTwo has two arguments. The ShowResult Sub
procedure uses this Function procedure by passing two arguments to it (in
parentheses). The ShowResult procedure then displays a message box showing
the value returned by the MultiplyTwo function.