错误LNK2019:未解析的外部符号

Question

我最近又开始用C++编程,为了教育目的,我正在创建一个扑克游戏.奇怪的是,我一直收到以下错误:

1>LearningLanguage01.obj : error LNK2019: unresolved external symbol "public: __thiscall PokerGame::Poker::Poker(void)" (??0Poker@PokerGame@@QAE@XZ) referenced in function "void __cdecl `dynamic initializer for 'pokerGame''(void)" (??__EpokerGame@@YAXXZ)
1>LearningLanguage01.obj : error LNK2019: unresolved external symbol "public: __thiscall PokerGame::Poker::~Poker(void)" (??1Poker@PokerGame@@QAE@XZ) referenced in function "void __cdecl `dynamic atexit destructor for 'pokerGame''(void)" (??__FpokerGame@@YAXXZ)
1>LearningLanguage01.obj : error LNK2019: unresolved external symbol "public: void __thiscall PokerGame::Poker::begin(void)" (?begin@Poker@PokerGame@@QAEXXZ) referenced in function _wmain
1>C:\Visual Studio 2012\Projects\LearningLanguage01\Debug\LearningLanguage01.exe : fatal error LNK1120: 3 unresolved externals

我已经对这个问题做了一些研究,大多数都指向头文件中的构造函数和析构函数定义,并且.cpp不匹配.我没有看到标题和.cpp的任何问题.

这是poker.h的代码:

#pragma once

#include "Deck.h"

using namespace CardDeck;

namespace PokerGame
{
    const int MAX_HAND_SIZE = 5;

    struct HAND
    {
        public:
            CARD cards[MAX_HAND_SIZE];
    };

    class Poker
    {
        public:
            Poker(void);
            ~Poker(void);
            HAND drawHand(int gameMode);
            void begin();
    };
}

和.cpp中的代码:

#include "stdafx.h"
#include "Poker.h"

using namespace PokerGame;

const int TEXAS_HOLDEM = 0;
const int FIVE_CARD = 1;

class Poker
{
    private:
        Deck deck;      

    Poker::Poker()
    {
        deck = Deck();
    }

    Poker::~Poker()
    {
    }

    void Poker::begin()
    {
        deck.shuffle();
    }

    //Draws a hand of cards and returns it to the player
    HAND Poker::drawHand(int gameMode)
    {
        HAND hand;

        if(gameMode == TEXAS_HOLDEM)
        {
            for(int i = 0; i < sizeof(hand.cards); i++)
            {
                hand.cards[i] = deck.drawCard();
            }
        }

        return hand;
    }

};

Answer 1

由于下面的评论,我改写了以前的评论.

链接器抱怨的问题是你已经声明了你的成员函数Poker,但还没有定义它们.这怎么样？对于初学者,您正在创建一个新类并在其中定义单独的成员函数.

您的头文件Poker类存在于PokerGame命名空间中,您的cpp文件Poker类存在于全局命名空间中.要解决该问题,请将它们放在同一名称空间中:

//cpp file
namespace PokerGame {
    class Poker {
        ...
    };
}

现在他们在同一名称空间中,你有另一个问题.您在类主体中定义了成员函数,但不是第一个.这些定义根本无法进入以相同方式命名的类的主体.摆脱cpp文件中的整个类:

//cpp file
namespace PokerGame {
    Poker::Poker() {
        deck = Deck(); //consider a member initializer instead
    }

    //other definitions
}

最后一件事:你把你班级的私人部分放在了错误的位置.我们刚刚删除了那个cpp文件类.它属于您班级的其他部分:

//header file
namespace PokerGame {
    class Poker {
    public:
        //public stuff

    private: 
        Deck deck; //moved from cpp file
   };
}