c++ - 我创建了 deque 并添加了不同类型的元素。我怎样才能改变这个元素的属性？

Question

我创造了:

class CMap:{
public
std::deque<CObject*> obiekty;
}


class CBullet{
public:
int damage;
}

并且我添加了不同类型的元素(例如 CTank、CBullet...)我想使用双端队列更改属性

for( size_t i=0; i<game->Mapa->obiekty.size(); i++){

 if(typeid(*(game->Mapa->obiekty[i]))==typeid(CBullet)){                                       
  this->HP=this->HP - game->Mapa->obiekty[i] (?? my problem/I can't do it ?? ->damage); 

}
}

Answer 1

首先你需要从基类(CObject)继承你的派生类(CBullet，CTank)，像这样

//Base clase
class CObject
{
public:
    //...
    virtual ~CObject(){}; // Don't forget about virtual desctructor
};
class CBullet: public CObject
{
public:
    //...
    ~CBullet(){};
    void DoBulletMethod(){};
};
class CTank: public CObject
{
public:
    //...
    ~CTank(){};
    void DoTankMethod(){};
};

然后你可以通过dynamic_cast检查所有对象，像这样:

for( size_t i=0; i< game->Mapa->obiekty.size(); i++)
{
    if(dynamic_cast<CBullet*>(game->Mapa->obiekty[i]) != nullptr)
    {
        CBullet * BulletObj = dynamic_cast<CBullet*>(game->Mapa->obiekty[i]);
        BulletObj->DoBulletMethod();
    }
    else if(dynamic_cast<CTank*>(game->Mapa->obiekty[i]) != nullptr)
    {
        CTank * TankObj = dynamic_cast<CTank*>(game->Mapa->obiekty[i]);
        TankObj->DoTankMethod();
    }
}

或者您可以使用多态性并创建虚方法，而无需进一步检测当前对象类型，例如在基类中创建一个虚方法并在派生类中覆盖它:

//Base clase
class CObject
{
public:
    //...
    virtual ~CObject(){}; // Don't forget about virtual desctructor
    virtual void DoActionInLoop()
    {
        //No action in base class
    }
};
class CBullet: public CObject
{
public:
    //...
    ~CBullet(){};
    virtual void DoActionInLoop() override
    {
        std::cout << "I am bullet I can do here my tasks" << std::endl;
    }
};
class CTank: public CObject
{
public:
    //...
    ~CTank(){};
    virtual void DoActionInLoop() override
    {
        std::cout << "I am tank and I can do here my tasks" << std::endl;
    }
};

然后只需在每个 CObject* 实例上调用此方法并获得您的多态性:

for( size_t i=0; i< game->Mapa->obiekty.size(); i++)
{
    game->Mapa->obiekty[i]->DoActionInLoop();
}