错误传递这个指针作为参数传递给类构造

Question

我有3类1）GameStateManager 2）MenuState（从称为游戏状态另一个类继承）3）游戏状态

欲这个指针作为参数传递到MenuState的构造。

我的目标是在MenuState中获取一个指向GameStateManager对象的指针，以备将来使用。

我得到错误：

error C2061: syntax error: identifier 'GameStateManager' 
error C2664: 'MenuState::MenuState(const MenuState &)': cannot convert argument 1 from 'GameStateManager' to 'const MenuState &' 
note: Reason: cannot convert from 'GameStateManager' to 'const MenuState' 

GameStateManager.h

#pragma once 

#include <vector> 
#include <SFML/Graphics.hpp> 
#include "MenuState.h" 

class GameStateManager { 
public: 
    static const int MENUSTATE = 0; 
    static const int FIRSTLEVELSTATE = 1; 

    GameStateManager(); 

    ~GameStateManager(); 
private: 
    std::vector<GameState*> States; 
    int currentState; 
}; 

GameStateManager.cpp

GameStateManager::GameStateManager() { 
    this->currentState = MENUSTATE; 
    this->States.push_back(new MenuState(*this)); // Error Line. I Think! 
} 

MenuState.h

#pragma once 
#include "GameState.h" 
#include "GameStateManager.h" 
class MenuState: public GameState{ 
public: 
    MenuState(GameStateManager& gsm); 
    ~MenuState(); 
}; 

MenuState.cpp

MenuState::MenuState(GameStateManager& gsm){ // Error Line. I Think! 
} 

GameState.h

#pragma once 
#include <SFML/Graphics.hpp> 
class GameState { 
//Virtual methods are here in this code which are not important for this question 
public: 
    GameState() {} 
    ~GameState() {} 
}; 

Main.cpp的

#include <SFML/Graphics.hpp> 
#include "GameStateManager.h" 

int main(int argc, char** argv) { 
    GameStateManager gsm; 
} 

Answer 1

由于像GameStateManager.h页眉列入冲突MenuState.h

使用转发声明，如果它们被声明为指针或引用：

1. MenuState::MenuState(class GameStateManager& gsm);
2. std::vector<class MenuState*> States;

然后，把行#include "GameStateManager.h"分成MenuState.cpp并把行#include "MenuState.h"分成GameStateManager.h会减少错误。