Gui на qt в виде dll

struct MyInterface {
    virtual int Add(int a, int b) = 0;
    virtual void Print() = 0;
};
 
extern "C" bool __declspec(dllexport) GetMyInterface(MyInterface** pMyInterface);
typedef bool(*GETINTF)(MyInterface** pMyInterface);
 
extern "C" bool __declspec(dllexport) FreeMyInterface(MyInterface** pMyInterface);
typedef bool(*FREEINTF)(MyInterface** pMyInterface);

bool GetMyInterface(MyInterface** pMyInterface) {
    if (!*pMyInterface) {
        *pMyInterface = new Gui(0);
        return true;
    }
    return false;
}
 
bool FreeMyInterface(MyInterface** pMyInterface) {
    if (!*pMyInterface) {
        return false;
    }
    delete *pMyInterface;
    pMyInterface = 0;
    app.exit();
    return true;
}

class Gui : public QObject, public MyInterface
{
    Q_OBJECT
 
public:
    Gui(QObject *parent);
    ~Gui();
 
public slots:
    int Add(int a, int b);
    void Print();
 
private:
    int argc;
    char** argv;
    //QApplication app;
    QTextEdit* textEdit;
};

Gui::Gui(QObject *parent)
    : QObject(parent), argc(0), argv(0)//, app(argc, argv)
{
    this->textEdit = new QTextEdit;
    this->textEdit->show();
 
    this->textEdit->append("I'm QT and I'm alive");
    //app.exec();
}
 
int Gui::Add(int a, int b) {
    this->textEdit->append("You check Add function");
    return a + b;
}
 
void Gui::Print() {
    this->textEdit->append("I'm QT and I can print everything");
}

int main()
{
    HINSTANCE hDll = LoadLibrary("Library.dll");
 
    MyInterface* myInterface = 0;
 
    if (hDll) {
        std::cout << "Dll load - successful" << std::endl;
 
        GETINTF GetMyInterface;
        GetMyInterface = (GETINTF)GetProcAddress(hDll, "GetMyInterface");
        if (!GetMyInterface) {
            std::cout << "Load F GetMyInterface - fail" << std::endl;
            FreeLibrary(hDll);
            _getch();
            return 0;
        }
 
        FREEINTF FreeMyInterface;
        FreeMyInterface = (FREEINTF)GetProcAddress(hDll, "FreeMyInterface");
        if (!FreeMyInterface) {
            std::cout << "Load F FreeMyInterface - fail" << std::endl;
            FreeLibrary(hDll);
            _getch();
            return 0;
        }
 
        GetMyInterface(&myInterface);
 
        std::cout << "My interface print - " << myInterface->Add(10, 5)<<std::endl;
        myInterface->Print();
 
        _getch();
 
        FreeMyInterface(&myInterface);
 
        std::cout << Add(2, 3) << std::endl;
        Print("a");
        PrintWSC("a");
 
    }
    else {
        std::cout << "Not load dll" << std::endl;
    }
    _getch();
    return 0;
}