Can I use forward declarations inside a DLL?

Question

I have a main project and a DLL project. The main executable links to the DLL. In the main project I have a function:

int func(char *str)
{
    .....
}

In the DLL project, I want to use this function. Can I forward declare this function and use it? Like:

int func(char *str);

int dllFunc()
{
    ...
    status = func(str);
    ...
}

Answer 1

You cannot use forward declaration forward declaration is something different. If you want call some method in dll, you have to use GetProcAdress or Implicit linking .

Anyway, It look that you want to call method placed inside you executable from some DLL, it can be done as far as I know. And it doesn't make much sense, because DLL is designed to be shared between application not main executable.

Answer 2

One (fairly common) way of doing it is to provide a callback from the application, ie

In DLL:

typedef void (*callback)();

callback my_callback;

void dll_register_callback(callback app_callback) { my_callback = app_callback; }

void do_things() { my_callback(); }

In application:

void cb() {}

dll_register_callback(cb);