topic Re: compiler directives with C++ in Intel® Fortran Compiler

compiler directives with C++

cfann61 — Thu, 18 Sep 2008 20:24:21 GMT

I'm trying to write a basic program in C++ that calls a routine and a function from Fortran. I found this example on the web ( http://www.neurophys.wisc.edu/comp/docs/notes/not017.html) and have been trying to duplicate it. I'm getting three errors when I try to build:

error: LNK2019: unresolved external symbol _Main__ referenced in function_main (coming from Fortran project)

error: LNK2019: unresolved external symbol _FF1@4 reference in function_main (coming from C++ project)

error: LNK2019: unresolved external symbol _FR1@8 reference in function_main (coming from C++ project)

My directives look like this for my subroutine:

!DEC$ ATTRIBUTES DLLEXPORT ::FR1

!DEC$ ATTRIBUTES STDCALL, ALIAS : '_FR1@8' :: FR1

And this for my function(which is in the subroutine)

!DEC$ ATTRIBUTES DLLEXPORT :: FF1

!DEC$ ATTRIBUTES STDCALL, ALIAS : '_FF1@4' :: FF1

C++ section looks like this:

extern "C" void _stdcall FR1(int*,int *);

extern "C" int _stdcall FF1(int *);

void main()

{

int n=10,nSq,nCube;

FR1(&n,&nSq);

nCube=FF1(&n);

}

Thanks

Chris

Re: compiler directives with C++

TimP — Fri, 19 Sep 2008 00:29:33 GMT

As stdcall is an obsolete ABI, support for it is not available in all Fortran compilers, nor is there a compatible default in those that have supported it in the last 5 years. I suspect you haven't attempted to turn it on on the Fortran side, nor would I recommend you try it. You don't show any motivation for avoiding Fortran 2003 C Interoperability method. If, for some reason, you don't want to use ISO C Interoperability, you still ought to avoid stdcall.

Re: compiler directives with C++

Steven_L_Intel1 — Fri, 19 Sep 2008 00:48:50 GMT

I'm not really in agreement that STDCALL is obsolete - it is the ONLY method available for calls to the Win32 API and from VB, EXCEL, managed code, etc.

There is at least one problem you have in that the Fortran project is looking for a main program. This means that either you created the Fortran project as an executable application (Console, etc.) rather than static library, or you have run into a bug in older versions of Intel Visual Fortran where every source got linked. Most likely the former.

You want to create a static library project for the Fortran code and make it a "dependent" of the C++ project. (If you have VS2005, make sure it also has SP1 applied.) In the Fortran project, set the property Libraries > Disable default library search rules to "No". Under Tools > Options > Projects > VC++ Directories, add the path to the Fortran installation LIB folder to "Library Files".

If in fact you have done all of these but still get the Fortran code linked, in the Fortran project go to the Fortran > Command Line property page and add /c to the Additional Options text.

Re: compiler directives with C++

cfann61 — Tue, 23 Sep 2008 14:50:16 GMT

Thanks.

I was initializing everything as console applications. Working fine now.