无法从类型基类的指针访问派生类方法

问题描述：

我应该指定我对OOP有点新。
我打算做一个类型指针的向量，有一个方法GetName（）和访问方法GetSpg（）从我的Player类派生Person。我得到一个错误GetSpg（）不是Person的成员。我的问题是：有没有办法从向量访问两个函数，如果它指向一个人不显示该方法，但如果这样做？

I should specify that I'm a bit new to OOP. I'm tying to make a vector of type pointer to Person that has a method GetName() and access a method GetSpg() from my Player class that derives Person. I get an error "GetSpg() is not a member of Person". My question would be: is there any way to access both functions from the vector so that if it points to a Person to not show that method but if it is to do so?

这是我的代码：

#ifndef _PERSON_H
#define _PERSON_H

#include <iostream>
#include <algorithm>

typedef std::pair<std::string, std::string> StrPair;

class Person :private StrPair
{

  public:
    Person(const std::string& fn = "none", const std::string& sn = "none")         :StrPair(fn,sn){};
    virtual void Update(const std::string& fn, const std::string& sn){ StrPair::first = fn; StrPair::second = sn; };
    virtual const StrPair& GetName(){ return (const StrPair&)(*this); };
};
#endif

typedef std::pair<int, int> IntPair;

class Jucator: public Person, private IntPair
{
    std::string tip;
    int spg;
    int average;

  public:
    Jucator(const std::string& fn = "none", const std::string& sn = "none", 
        const std::string& t = "", const int& _spg = 0, const int& _avr = 0, 
        const int& _g = 0, const int& _r = 0) :Person(fn, sn),tip(t),spg(_spg),average(_avr),IntPair(_g,_r){};
    virtual void Update(const std::string& fn, const std::string& sn, const std::string& t, const int& _spg, const int& _avr,
        const int& _g, const int& _r){
    Person::Update(fn, sn); tip = t; spg = _spg; average = _avr; IntPair::first = _g; IntPair::second = _r;
};

virtual const int& GetSpg(){ return spg; };

答

>
Person 类型的指针只能用于访问作为 Person $的一部分的数据/地址c $ c> object。编译器根本无法知道从 Person 中导出的所有类是什么，因此哪些操作是合法的。

You can't. A pointer of type Person can only be used to access data/addresses(functions) that are part of the Person object. The compiler simply has no way of knowing what all classes could be deriving from Person and hence which operations are legal.

看看动态投射。 MSDN参考 | 教程

Have a look at Dynamic casting. MSDN Reference | Tutorial

简要说明：

Player* pPlayer = dynamic_cast<Player*>(pPerson);
if (pPlayer) {
  //Use the pointer like a player pointer
  //Note: You can only call player functions from pPlayer, not pPerson
} else {
  //Use the pointer like a person pointer
}

运行时操作。在编译时，编译器会使用 Player 指针访问 Player 代码，它很高兴允许！

Note that this casting is a runtime operation. At compile time, the compiler sees you using the Player pointer to access Player code, which it is happy to allow!

免责声明：我发现您的代码很难遵循，因此请考虑这是您在文本中的问题的回答

无法从类型基类的指针访问派生类方法

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