Little problem interfacing VB and Fortran

[CharlesDayan]

I'm trying to send two arrays (a double and a long) from VB to a FORTRAN DLL. I don't understand why I can get (without problems) all variables but my array of longs? The DLL returns the same array; it accepts the call but doesn't perform any calculation with the array!!???

Here the short code:

Subroutine VB_FOR(x,n,m,r,xx,nn,mm,rr)
implicit none
!
!MS$ATTRIBUTES DLLEXPORT :: VB_FOR
!MS$ATTRIBUTES ALIAS : 'VB_FOR' :: VB_FOR
!
Real(8) , intent(inout) :: x
Integer(2) , intent(in) :: n
Integer(2) , intent(in) :: m
Real(8) , intent(inout) :: r

Integer(4) , intent(inout) :: xx
Integer(2) , intent(in) :: nn
Integer(2) , intent(in) :: mm
Integer(4) , intent(inout) :: rr

dimension x(n,m) ! dimension of the array of doubles
dimension xx(nn,mm) ! ... array of longs

integer :: i
integer :: j

do i=1,n
do j=1,m
x(i,j)=x(i,j)*n/10 ! WORKS FINE
end do
end do

r=2.13*r*r ! WORKS FINE

do i=1,nn
do j=1,mm
xx(i,j)=xx(i,j)*xx(i,j) ! DO NOT WORK (?)
end do
end do

rr=rr*rr ! WORKS FINE

end subroutine

The Visual Basic 6 side:

Private Declare Sub VB_FOR Lib "VB_FOR.dll" (ByRef Array_Dbl As Double, ByRef Linha_Dbl As Integer, ByRef Coluna_Dbl As Integer, ByRef Duplo_Dbl As Double, ByRef Array_Lng As Long, ByRef Linha_Lng As Integer, ByRef Coluna_Lng As Integer, ByRef Longo_Lng As Long)

Sub CallDLL_Click()
.
.
.
Call VB_FOR(MyDblArr(1, 1), n, m, My_Double, MyLngArr(1, 1), nn, mn, My_Long)
.
.
.
End Sub


ANY SUGGESTION ?

 

[xwb]

What is the difference in size between Integer and Long in VB?

 

[CharlesDayan]

Do you mean: Integer[vb] <=> Integer(2)[fortran]
Long[vb] <=> Integer(4)[fortran]

 

[xwb]

No - you are perfectly right: VB Integer = INTEGER*2 and VB Long = INTEGER*4.

Why not try a 1 dimensional array first - see if that works with longs?

I'm just guessing here as I don't have an MS environment.

 

[CharlesDayan]

It is incredible, your hint worked! The program works for 1 dimensional arrays (vectors)! But the mystery continues !

 

[xwb]

Try a 1D array in VB and access it as a 2D array in Fortran. Also try a 2D array in VB and access it as a 1D array in Fortran.

If the latter works, then you may have to do some computation on the indices (xx(a,b) (VB) = xx((a - 1) * bmax + b) (Fortran).

At a guess, it is something to do with the implementation of 2D arrays - they are probably not the same in both languages. Can't think of anything else.

 

[CharlesDayan]

1- Nop! I can't access send the arrays with different dimensions!

2- The array definitions between VB (not VBNet) and Fortran are the same! If I declare explicitly (i.e. dimension xx(11,33) ! ... array of longs) the program works.

Let me put my problem again: I want to pass a array from VB to fortran, but the fortran dll has no previous knowledge about the array dimension.

ANY SUGGESTIONS ABOUT THE USE OF POINTERS WILL BE APPRECIATE