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User Defined Functions

  Asked By: Pedro    Date: Jan 24    Category: MS Office    Views: 1754

I'm trying to learn how to write functions for use in Excel. For
example, one function I'd like to write would take as an argument a
one dimensional range, either an array or a vector.

To create a function for use in Excel, I understand that I have to do
the following:

Function Truncate(InitialRange)


End Function

First, how can I check that the variable InitialRange is a reference
to cells in the spreadsheet (e.g. "=Truncate(B6:B12)"), and not a
number or a string (e.g. "Truncate(6)")? Is VBA in any way a typed

Once that is done, how do I access the values in the range? I want to
check each value to make sure it satisfies a constraint; for example,
all cells must be under 100.

Finally, I want to return a new range that is a subset of InitialRange.

Please let me know if you can help me, or if I need to clarify this in
any way.



1 Answer Found

Answer #1    Answered By: Waggoner Fischer     Answered On: Jan 24

>First, how can I check  that the variable  InitialRange is a reference
>to cells  in the spreadsheet  (e.g. "=Truncate(B6:B12)"), and not a
>number or a string  (e.g. "Truncate(6)")?

In code, you can use functions  such as:

During debugging, you can see the Type of everything in the locals
window if you set a breakpoint.

>Is vba  in any way a typed

Yes, but it has a default type called Variant that can morph into
whatever type is expected by the code. Unless declared otherwise,
variables are Variants.

>Once that is done, how do I access  the values  in the range?

Here is an example  of a function  that returns Boolean values (e.g.
to the spreadsheet or another function or subroutine):

Function Test2(x)
a = x 'this is a trick to convert a range  object to a variant
NRows = UBound(a, 1)
NCols = UBound(a, 2)
ReDim b(1 To NRows, 1 To NCols)
For r = 1 To NRows
For c = 1 To NCols
b(r, c) = a(r, c) < 100
Test2 = b
End Function

>Finally, I want to return a new range that is a subset of

The above example returns values (e.g. for use in the spreadsheet).
If you want to return a Range Collection instead of values (e.g. for
use in another code block), look at the Range Collection, Offset and
Union methods in Excel help.

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