Calling a dll from fortran - dll

Question

I am aiming at calling a dll file from a fortran compiler. I am doing all this in windows using the mingw compiler.
The dll was created using a g++ compiler
The code for which I am trying to create a dll
// example_dll.cpp
#include <stdio.h>
#include "example_dll.h"
__stdcall void hello()
{
printf("Hello");
}
command entered in the command prompt
g++ -c -DBUILDING_EXAMPLE_DLL example_dll.cpp
g++ -shared -o example_dll.dll example_dll.o -Wl,--out-implib,libexample_dll.a
The above two commands creates the dll file.
The job now is to create a fortran script to compile the dll file previously created.
For this purpose I am looking forward to create a fortran file capable of linking to the dll previously created.
Any help will be appreciated.
Thanks,
Adarsh

Answer 1

Later I tried some of the possibilities. My updated files are as follows
C file for which the DLL is created is as follows
// example_dll.c
#include <stdio.h>
#include "example_dll.h"
EXPORT void tstfunc (void)
{
printf("Hello\n");
}
EXPORT int Double11(int x)
{
printf("From the Double11\n");
printf("%d\n",x);
return x;
}
.h file used to create the DLL is as follows
// example_dll.h
#ifdef EXAMPLE_DLL_H
// the dll exports
#define EXPORT __declspec(dllexport)
#else
// the exe imports
#define EXPORT __declspec(dllimport)
#endif
// function to be imported/exported
EXPORT void tstfunc (void);
EXPORT int Double11(int x);
Fortran file used to link the dll is as follows
! fortcall.f90
program ForCall
IMPLICIT NONE
integer :: sum
integer :: inte3
INTERFACE
SUBROUTINE write() BIND(C,NAME='tstfunc')
END SUBROUTINE write
END INTERFACE
INTERFACE
SUBROUTINE get_integer(inte,inte2) BIND(C,NAME='Double11')
USE ISO_C_BINDING
IMPLICIT NONE
INTEGER (C_INT), VALUE :: inte
INTEGER (C_INT), INTENT(OUT) :: inte2
END SUBROUTINE get_integer
END INTERFACE
CALL write
CALL get_integer(1,inte3)
print*,"the output is",inte3
END PROGRAM ForCall
After entering the following directive in the command prompt
gfortran -o dll_foo_test fortcall.f90 -L. example_dll.dll
The output will be as follows
Hello
From the Double11
1
the output is -2
At this point something is not right. The code is capable of passing a value from FORTRAN to the DLL, whereas the code is not returning the right value from the dll. Some junk value of -2 is being displayed instead of 1.
I would like to fix that part in the code.