struct ClassName
{
    static SDL_Joystick* controller;
    static Sint16 axis_x, axis_y;

    inline static void set_axis(const SDL_Event& e)
    {
        if(e.jaxis.which == 0) {
            axis_x = SDL_JoystickGetAxis(controller, 0); // 0 indicates x
            axis_y = SDL_JoystickGetAxis(controller, 1); // 1 indicates y
        }
    }
};

while(SDL_PollEvent(&e)) {
    // ..
    if(ClassName::controller)
        if(e.type == SDL_JOYAXISMOTION) ClassName::set_axis(e);
}

printf("X: %d Y: %dn", ClassName::axis_x, ClassName::axis_y);