Question

My managed c++ code fails to compile with the error message

.Window.cpp(11) : error C2440:  initializing  : cannot convert from  System::Windows::Forms::Form ^  to  Enviroment::Window ^ 
        No user-defined-conversion operator available, or
        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
.Window.cpp(11) : error C3754: delegate constructor: member function  Enviroment::Window::_keydown  cannot be called on an instance of type  System::Windows::Forms::Form ^ 

Error   1   error C2440:  initializing  : cannot convert from  System::Windows::Forms::Form ^  to  Enviroment::Window ^     c:UsersThomasDocumentsVisual Studio 2008ProjectsProject_XProject_XWindow.cpp    11
Error   2   error C3754: delegate constructor: member function  Enviroment::Window::_keydown  cannot be called on an instance of type  System::Windows::Forms::Form ^   c:UsersThomasDocumentsVisual Studio 2008ProjectsProject_XProject_XWindow.cpp    11

In window.h

ref class Window
    {
    public:
        Window();
        void _keydown(System::Object^ sender, System::Windows::Forms::KeyEventArgs^ e);
    }

In window.cpp

Window::Window()
    {
        Form^ form = gcnew Form();
        form->KeyDown+= gcnew KeyEventHandler(form, &Window::_keydown);
}

and later

void Window::_keydown(System::Object^ sender, System::Windows::Forms::KeyEventArgs^ e)
    {
        //stuff
    }

Help!

Answer 1

I think you mean to say:

form->KeyDown+= gcnew KeyEventHandler(this, &Window::_keydown);

In C++, a class function pointer is comprised of 2 things, the actual pointer (this part you got right) and a pointer to "this" to be passed to the function, which is of the type of the class holding the function. This is your Window, not Microsoft s Form.

友情链接