鍍金池/ 問答/C++/ 兩個(gè)類交叉引用引起的錯(cuò)誤,求看看呀?

兩個(gè)類交叉引用引起的錯(cuò)誤,求看看呀?

/*================================================================

  • Copyright (C) 2017 Ltd. All rights reserved.
  • FileName:fsm.cpp
  • Author: shrekshen
  • Create-time:2017-12-19 20:18:03
  • Describle:study fsm, reference:http://blog.csdn.net/popy007/...

*
================================================================*/

include <iostream>

include <map>

using namespace std;

class Fsm;//前置聲明
//首先創(chuàng)建一個(gè)gamestate類,它是其他狀態(tài)類的基類
enum E_GAME_STATE
{

E_INTO_GAME = 0,
E_PLAY_GAME = 1,
E_LEFT_GAME = 2

};

class GameState
{

public:
    virtual ~GameState(){}
    virtual void drive() = 0;
    GameState(Fsm* fsm)
    {
        m_fsm = fsm;
    }
    Fsm *m_fsm;

};

//然后添加一個(gè)管理這些類的管理類,也就是狀態(tài)機(jī)
class Fsm
{

public:
    void add_state(E_GAME_STATE gameState , GameState *state)
    {
        state_map.insert(pair<E_GAME_STATE, GameState *>(gameState, state));
    }
    
    void switch_state(E_GAME_STATE gameState)
    {
        std::map<E_GAME_STATE, GameState *>::iterator it = state_map.find(gameState);
        current_state = it->second;
        current_state->drive();
    }

protected:
    std::map<E_GAME_STATE, GameState *> state_map;
    GameState *current_state;

};

class IntoGameState : public GameState
{

public:
    IntoGameState(Fsm *fsm):GameState(fsm)
    {
    
    }
public:
    virtual void drive()
    {
        cout << "IntoGameState" << endl;
        m_fsm->switch_state(E_PLAY_GAME);
    }

};

class PlayGameState : public GameState
{

public:
    PlayGameState(Fsm *fsm):GameState(fsm)
    {
    
    }

public:
    virtual void drive()
    {
        cout << "PlayGameState" << endl;
        m_fsm->switch_state(E_LEFT_GAME);
    }

};

class LeftGameState : public GameState
{

public:
    LeftGameState(Fsm *fsm):GameState(fsm)
    {

    }

public:
    virtual void drive()
    {
        cout << "LeftGameState" << endl;
        m_fsm->switch_state(E_INTO_GAME);
    }

};

int main(){

Fsm *fsm = new Fsm;
GameState *intostate = new IntoGameState(fsm);
GameState *playstate = new PlayGameState(fsm);
GameState *leftstate = new LeftGameState(fsm);
fsm->add_state(E_INTO_GAME, intostate);
fsm->add_state(E_PLAY_GAME, playstate);
fsm->add_state(E_LEFT_GAME, leftstate);
fsm->switch_state(E_LEFT_GAME);

}

最近在學(xué)習(xí)設(shè)計(jì)模式,寫的一個(gè)簡(jiǎn)單的狀態(tài)機(jī),遇到了這個(gè)問題,麻煩各位看看。

class Fsm;//前置聲明
//首先創(chuàng)建一個(gè)gamestate類,它是其他狀態(tài)類的基類
enum E_GAME_STATE
{

E_INTO_GAME = 0,
E_PLAY_GAME = 1,
E_LEFT_GAME = 2

};

class GameState
{

public:
    virtual ~GameState(){}
    virtual void cycle() = 0;
    virtual void drive()=0;
    GameState(Fsm* fsm)
    {
        m_fsm = fsm;
    }
    Fsm *m_fsm;

};

class IntoGameState : public GameState
{

public:
    virtual void drive(Fsm *fsm)
    {
        m_fsm = fsm;
        cout << "IntoGameState" << endl;
        m_fsm->switch_state(E_LEFT_GAME);
    }

};

class PlayGameState : public GameState
{

public:
    virtual void drive(Fsm *fsm)
    {
        m_fsm = fsm;
        cout << "PlayGameState" << endl;
        m_fsm->switch_state(E_LEFT_GAME);
    }

};

class LeftGameState : public GameState
{

public:
    virtual void drive(Fsm *fsm)
    {
        m_fsm = fsm;
        cout << "LeftGameState" << endl;
        m_fsm->switch_state(E_INTO_GAME);
    }

};

//然后添加一個(gè)管理這些類的管理類,也就是狀態(tài)機(jī)
class Fsm
{

public:
    add_state(E_GAME_STATE gameState , GameState *state)
    {
        state_map.insert(gameState, state);
    }
    
    switch_state(E_GAME_STATE gameState)
    {
        std::map<E_GAME_STATE, GameState *> it = state_map.find(gameState);
        current_state = it->end();
        current_state->drive(Fsm);
    }

private:
    std::map<E_GAME_STATE, GameState *> state_map;
    GameState *current_state;

};

int main(){

Fsm *fsm = new Fsm;
GameState *intostate = new IntoGameState(fsm);
GameState *playstate = new PlayGameState(fsm);
GameState *leftstate = new LeftGameState(fsm);
fsm->add_state(E_INTO_GAME, intostate);
fsm->add_state(E_PLAY_GAME, playstate);
fsm->add_state(E_LEFT_GAME, leftstate);
fsm->switch_state(E_LEFT_GAME);

}

回答
編輯回答
浪婳

首先, 你需要展示自己在解決這個(gè)問題的過程中做出了哪些嘗試, 搜了哪些東西, 得出些什么結(jié)論. 而不是這樣就扔個(gè)代碼.
先把這篇帖子讀了: https://stackoverflow.com/que...

為了充實(shí)下此答案, 稍微結(jié)合下你的問題說下, 雖然沒什么意義, 因?yàn)槟瞧诱f的很好了, 不過沒有引用標(biāo)準(zhǔn),
語言律師可能不是很喜歡, 所以我再補(bǔ)充些標(biāo)準(zhǔn)里的. (這是符合stackexchange的規(guī)則的, 因?yàn)槲医o出了原鏈):

雖然有了前置聲明, 但是編譯器并不知道Fsm的大小, 成員, 方法. 它此時(shí)被稱作incomplete type, 它是不能被解引用的(operator->其實(shí)也是解引用符), 所以你用vs的話雙擊error會(huì)調(diào)到幾行解引用的地方, compile time error了.

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2018年5月21日 00:13