If you are compiling using a C++ compiler, you will need to use

external "C" {

double myfunc(double d) {

  return d;

}

}

Or similar in your C++ code. If you don't, the function is not visible from the Modelica code since it only looks for C functions.

Hello hu72005

Welcome to the Forum!

Please detail us the problems you have had.

Best regards
Koldo

Thanks for your quick reply sjoelund.se , I am trying to use Visual c++ file I am able to access simple function from vc++ file but  having trouble  in calling COM dll methods.

Note that OpenModelica uses MinGW, which will give you trouble trying to use some Windows API's. As I am a Linux user myself I can not help you much further.

hu72005@gmail.com wrote:

Thanks for your quick reply sjoelund.se , I am trying to use Visual c++ file I am able to access simple function from vc++ file but  having trouble  in calling COM dll methods.

Hello hu72005

As sjoelund.se has said, it is easier to work with MinGW. There is a copy of it bundled with OpenModelica. It is very easy to use it but you can ask if you have problems using it.

You say that you have problems calling DLLs. Does it mean that you have a DLL and you want to call it from OpenModelica?. That would be easy too. Please confirm if this is your problem.

Best regards
Koldo

Yes Koldo, exactly.
I want to call dll function in openmodelica

Hello hu72005

If you know how to run your external C code from OpenModelica, you just need to create a .C file with a function like this:

#include <windows.h>

static HINSTANCE hinstLib = 0;
static double (* MyFunctionPointer)(double) = 0;

double MyFunction(double arg) {
    if (hinstLib == 0)
        hinstLib = LoadLibraryEx(TEXT("MyDLLFullFilePath"), NULL, LOAD_IGNORE_CODE_AUTHZ_LEVEL); // Loads the DLL
    if (MyFunctionPointer == 0)
        MyFunctionPointer = GetProcAddress(hinstLib, "MyFunctionName");  // Loads the function pointer
    return (*MyFunctionPointer)(arg);  // Calls it
}

This is in Windows. In Linux this is also possible to be done as easily calling dynamic libraries.

Best regards
Koldo

Hello hu72005

If you know how to run your external C code from OpenModelica, you just need to create a .C file with a function like this:

#include <windows.h>

static HINSTANCE hinstLib = 0;
static double (* MyFunctionPointer)(double) = 0;

double MyFunction(double arg) {
    if (hinstLib == 0)
        hinstLib = LoadLibraryEx(TEXT("MyDLLFullFilePath"), NULL, LOAD_IGNORE_CODE_AUTHZ_LEVEL); // Loads the DLL
    if (MyFunctionPointer == 0)
        MyFunctionPointer = GetProcAddress(hinstLib, "MyFunctionName");  // Loads the function pointer
    return (*MyFunctionPointer)(arg);  // Calls it
}

This is in Windows. In Linux this is also possible to be done as easily calling dynamic libraries.

Best regards
Koldo