class OnScreenObject{  private:  public:    int x, y;    SDL_Surface* img;    void load(const string &fname);        OnScreenObject(void)    : img(0),      x(0), y(0)    {  }};class ClickableObject : public OnScreenObject{  private:  public:    void (*onClick) (void);        ClickableObject(void)    : onClick(0)    { OnScreenObject::OnScreenObject(); }};  

  ClickableObject(){   // The following will create a temporary OnScreenObject   // on the stack, that will be deleted at the end of the   // statement.   OnScreenObject::OnScreenObject();}  

  // The following will explicitly call the constructor of// the base type.ClickableObject() : OnScreenObject(){}  

  // The following will implicitly call the constructor of// the base type.ClickableObject(){}