c++ - 在 C++ 中实现纯虚类的问题

Question

我有以下类(class):

#include <string>
#include <stack>
#include <queue>
#include "map.h"

using namespace std;

#ifndef CONTAINER_H_
#define CONTAINER_H_

struct PathContainer {
    int x, y;
    string path;
};

class Container {
public:
    virtual void AddTile(string, FloorTile *) = 0;
    virtual void ClearContainer() = 0;
    virtual PathContainer *NextTile() = 0;
};

class StackImpl : public Container {
private:
    stack<PathContainer> cntr;
public:
    StackImpl();
    void AddTile(string, NeighborTile *);
    void ClearContainer();
    PathContainer *NextTile();
};

class QueueImpl : public Container {
private:
    queue<PathContainer> cntr;
public:
    QueueImpl();
    void AddTile(string, NeighborTile *);
    void ClearContainer();
    PathContainer *NextTile();
};
#endif

当我尝试像这样创建 StackImpl 或 QueueImpl 对象时:

Container *cntr;
cntr = new StackImpl();

或

Container *cntr;
cntr = new QueueImpl();

编译时出现以下错误:

escape.cpp: In function ‘int main(int, char**)’:escape.cpp:26: error: cannot allocate an object of abstract type ‘StackImpl’container.h:23: note: because the following virtual functions are pure within ‘StackImpl’:container.h:18: note: virtual void Container::AddTile(std::string, FloorTile*)

有什么想法吗？

Answer 1

typeid(NeighborTile *) != typeid(FloorTile *)。签名不同，因此即使 NeighborTile 继承自 FloorTile，它们也不算作“相同”方法。