#VALUE error when dealing with long string in UDF in VBA(excel)

Question

I've encountered #VALUE error when using an UDF returning an array with long strings (>256 symbols).

Sample Code:

Function longString() As Variant
        Dim res(1 To 1, 1 To 2)
        res(1, 1) = "hellohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\nhellohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\nhellohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\nhellohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhellohh\n"
        res(1, 2) = "world"
        longString = res
End Function

When calling longString() as an array formula in a cell, the cell got #Value error, but through debugging, longString() returns without error.

how can i resolve this issue?

Answer 1

I believe you have run into one of the obscure limitations in the interactions between VBA and Excel.

One workaround would be to change the formula to return only a single element, and have the particular element as an argument in the UDF.

For example:

---

Option Explicit
Function longString(Optional R As Long = 1, Optional C As Long = 1)
        Dim res(1 To 1, 1 To 2)
        res(1, 1) = "hellohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\nhellohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\nhellohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\nhellohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhellohh\n"
        res(1, 2) = "world"
        longString = res(R, C)
End Function

---

You could then call the function in any of the following ways:

=longString()      <-- returns the first element
=longString(1,1)   <-- returns the first element
=longString(1,2)   <-- returns the second element
=longString(ROWS($1:1), COLUMNS($A:A))  <--could be dragged down and right to return an array of the elements