Convert C++ function pointer to c function pointer

Question

I am developing a C++ application using a C library. I have to send a pointer to function to the C library.

This is my class:

 class MainWindow : pub         


        

Answer 1

@Snps answer is great. I extended it with a maker function that creates a callback, as I always use void callbacks without parameters:

typedef void (*voidCCallback)();
template
voidCCallback makeCCallback(void (T::*method)(),T* r){
  Callback::func = std::bind(method, r);
  void (*c_function_pointer)() = static_cast(Callback::callback);
  return c_function_pointer;
}

From then on, you can create your plain C callback from within the class or anywhere else and have the member called:

voidCCallback callback = makeCCallback(&Foo::print, this);
plainOldCFunction(callback);