Passing array of characters from Fortran DLL to VBA

[Lorenzo_W_]

I am trying to link a Fortran DLL to VBA.

I started by using Intel example (https://software.intel.com/en-us/node/611723) and I am able to deal with all kind of data except array of strings.

Here is my example:

FORTRAN:

SUBROUTINE TESTARRAY (ELEMENTS, OUTARRAY) ! bind(c, name='TESTARRAY')
!DEC$ ATTRIBUTES DLLEXPORT, STDCALL, REFERENCE, ALIAS:"TESTARRAY" :: TESTARRAY

IMPLICIT NONE

INTEGER*4, INTENT(IN) :: ELEMENTS
CHARACTER*15, INTENT(OUT) :: OUTARRAY(ELEMENTS)
INTEGER*4:: I
!DEC$ ATTRIBUTES REFERENCE :: ELEMENTS, OUTARRAY

DO I = 1,ELEMENTS
    WRITE(OUTARRAY(I),'(I3.3)') I
ENDDO

RETURN

END SUBROUTINE TESTARRAY

------------------

VBA:

Option Explicit
Option Base 1

Dim arraytest() As String * 15

Declare Sub TESTARRAY Lib "PATH\MYDLL.dll" (ELEMENTS As Long, ByVal OUTARRAY As String)

Public Function array_dll(iel As Long) As String

   ReDim arraytest(1 To iel)

    Call TESTARRAY(iel, arraytest(1))

    array_dll = Trim(arraytest(iel))

End Function

When I try to use inside an Excel sheet the function "array_dll" linked to a cell containing for example "5", I obtain an empty cell, and not "005" as expected.

How is the right method for dealing with that kind of data?

Thank you!

[Steve_Lionel]

There is a complete example VB.NET-Safearrays in the Intel sample bundle that demonstrates doing exactly this. It's a lot more complicated than what you show above.

[Lorenzo_W_]

Thank you for the hint.

It is a lot more complicated than I thought, maybe I should try a workaround.
Thank you again

[FortranFan]

Lorenzo W. wrote:

.. It is a lot more complicated than I thought, maybe I should try a workaround ..

@Lorenzo W.,

How is the actual argument (i.e., the object equivalent to arraytest in your example above) used in the VBA code?  Specifically, does it have to be an array?

[DavidWhite · Accepted solution]

For simple cases passing multiple strings (not just arrays), I have sometimes just concatenated the strings on the VBA side and then unpacked them on the DLL side. (and of course, the reverse for passing the strings back).

[Lorenzo_W_]

Dear all,
I think that I can re-think about my output.

As David White suggested me, the best think I can do is to concatenate and then unpack strings, it is more simple than all other solutions.

Thank you all