I cannot access the values inside the Fortran labelled common blocks and I haven't found any example about this problem.
I'm able to call the Fortran routine that I've put inside a module but I cannot access to the Common Block Variables and notwithstanding several attempts I've always got zeros for the variables in common blocks.
I've created two separate projects one for C++ Console and one for Fortran dynamic link library inside a solution, in which the C++ project depends on the Fortran project.

Thank You very much for your answers in advance.


Carlo Timossi

What I have tried:

C++ code:

#include <iostream>

typedef struct
{
    short int   nstream;
    short int   nunit;
    short int   ncomp;
}  generaltype;

typedef struct 
{
    float tau;
} PItype;

extern "C" {
    generaltype general;
    PItype pi;
}

extern "C" {
    void ADD1(void);
}


int main()
{
    ADD1();
    std::cout << general.ncomp;
    std::cout << general.nunit;
    std::cout << general.ncomp;
    std::cout << pi.tau;
}

module testfor
    use, intrinsic :: iso_c_binding
    implicit none
contains
    subroutine ADD1() bind(C,name="ADD1")
    !DEC$ ATTRIBUTES DLLEXPORT:: ADD1
    implicit none
    include "Comm.for"
    nstream=5
    nunit=1
    ncomp=3
    tau = 3.14159
    return
    end subroutine
end module testfor

REAL tau
     !DEC$ ATTRIBUTES alias:'pi' :: pi
     COMMON /pi/ tau
     INTEGER(2) nstream, nunit, ncomp
     !DEC$ ATTRIBUTES alias:'general' :: general
     COMMON /general/ nstream, nunit, ncomp