/*对于此类的模型为:class object{    float _x;//类的nonstatic成员函数    _vptr_Point;//指向虚函数表的指针}virtual table//虚函数表的信息（应该存放的是一些指针）slot1---type info for Point(用于支持RTTI)slot2---~Point()slot3---print()类之外//成员函数Point::Point(float)float x() const//static函数static int PointCount()//static数据成员static int _point_count*/#include <iostream>class Point    {public:    Point(float xval);    virtual ~Point();    float x() const;    static int PointCount();protected:    virtual std::ostream& print(std::ostream& os) const;    float _x;    static int _point_count;};