Calling Fortran-DLL from Visual-Basic 6

fobermaier · ‎10-14-2005

Hello everyone,

I'm again having trouble calling a fortran-dll from VB6:
Here is the function definition:

logical(2) function CMaToV3Mat( cFile, pMat, iOF, iOT, iDF, iDT )

!DEC$ ATTRIBUTES DLLEXPORT, ALIAS:'CMaToV3Mat' :: CMaToV3Mat

!DEC$ ATTRIBUTES VALUE	:: iOF, iOT, iDF, iDT

implicit none
type (T_MATRIX), pointer :: pMat
character(len = *) :: cFile
integer(4) :: iOF, iOT, iDF, iDT
end function

Here is the vb6 declaration:

Private Declare Function CMaToV3Mat _
  Lib "C:VENUSivv3bV3V3ASSSimV3MatR.DLL" ( _
  ByVal strFileName As String, ByRef hMatrix As Long, _
  ByVal lngOrigFrom As Long, ByVal lngOrigTo As Long, _
  ByVal lngDestFrom As Long, ByVal lngDestTo As Long, _
  ByVal lngLenFilename As Long) As Boolean

Compiler Options are (IVF9)

/nologo /Zi /Od /GB /module:"$(INTDIR)/" /object:"$(INTDIR)/"
  /traceback /check:bounds /libs:dll /dbglibs /winapp /c /dll

I'm getting a runtime error #49, invalid calling convention.
Any ideas?
Thanks in advance
Felix Obermaier

Message Edited by fobermaier on 10-14-2005 10:03 AM

Message Edited by fobermaier on 10-14-2005 10:10 AM

Jugoslav_Dujic · ‎10-14-2005

AFAIK VB6 default for externals is __stdcall, but IVF default is __cdecl. So, a STDCALL attribute should sort it out.

Also, pay attention to pMat argument; since it's a pointer, in C terms, it matches a void** (T_MATRIX**), so on VB side its equivalent (actual argument) should be an address of an integer variable which holds address of a T_MATRIX (rather than mere address of a T_MATRIX). I don't know how to spell it in VB though.

Jugoslav

fobermaier · ‎10-14-2005

Thanks for the hint, Jugoslav. I've added

/iface:cvf /iface:nomixed_str_len_arg

to the command line options and now everything works fine.
Felix Obermaier