//如下示例
class?Coordinate{
public:
????double?getX();
????void?setX(_x);
private:
????double?X;
};

inline?double?Coordinate::getX(){return?X;}
inline?void?Coordinate::setX(_x){return?X;}
int?main(){
????Coordinate?coor;
????coor.setX(5);??????????????<=>?????coor.X=5
????cout<<coor.getX()<<endl;???<=>?????coor.X?????//X處在private
}