一般在游戏中，我们会有这样的定义Player和怪物NPC：        

// 基类 Character
class Character {
protected:
    std::string name;
    int64_t     id;
    int32_t     hp;
    int32_t     mp;
    int32_t     level;
    
public:
    Character(const int64_t name) : id(id) {}

    virtual void attack() {
        std::cout << id<< " attacks!" << std::endl;
        //....
    }

    virtual void defend() {
        std::cout << id<< " defends!" << std::endl;
        //....
    }
    void addhp(int32_t modhp){
        hp += modhp;
    }
    //.....
};

// 玩家类 Player
class Player : public Character {
public:
    Player(const int64_t  id) : Character(id) {}

    void attack() override {
        std::cout << name << " attacks with a powerful sword!" << std: