将 C++ 函数指针转换为 c 函数指针

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

这是我的课:

 class MainWindow : public QMainWindow {  
     Q_OBJECT  
     public:  
     explicit MainWindow(QWidget *parent = 0);  
     private:  
     Ui::MainWindow *ui;
     void f(int*);

 private slots:
     void on_btn_clicked(); 
};

这是我的 on_btn_clicked 函数:

void MainWindow::on_btn_clicked()
{
    void (MainWindow::* ptfptr) (int*) = &MainWindow::f;

    c_library_function(static_cast<void()(int*)>(ptfptr), NULL);

}