鏈接器錯誤-未定義參考

Question

我正在創建一個程序，但是運行它時出現以下錯誤：

/tmp/ccYLF4IM.o: In function `main':
maingame.cpp:(.text+0x13): undefined reference to `Human::Human()'
maingame.cpp:(.text+0x1f): undefined reference to `Orc::Orc()'
maingame.cpp:(.text+0x99): undefined reference to `Orc::~Orc()'
maingame.cpp:(.text+0xac): undefined reference to `Orc::~Orc()'
maingame.cpp:(.text+0xc5): undefined reference to `Human::~Human()'
maingame.cpp:(.text+0xdf): undefined reference to `Human::~Human()'
collect2: ld returned 1 exit status

我查看了我的代碼，我正在一起運行所有.cpp文件和.h文件。 我不確定是什么問題。 我知道與此有關的其他問題，但我似乎找不到所需的答案。 我檢查了所有內容的大小寫，甚至刪除了所有內容，然后再次開始以確保。 任何幫助，將不勝感激。 謝謝

//main.cpp
#include "Human.h"
#include "Orc.h"

using namespace std;

//Main.cpp
int main()
{
    //Character cc;
    Human H;
    Orc O;
    char choice;
    char userC;
    cout << "Welcome!\n";
    cout << "" << endl;

    cout << "Pick your choice:\n";
    cout << "A -- Human\n";
    cout << "B -- Orc\n";
    cin >> choice;

    return 0;
}

---

//Character.h
#ifndef CHARACTER_H
#define CHARACTER_H

#include <iostream>
#include <string>

using namespace std;

class Character
{
    protected:
                float characterTotal;
    public:                 
                virtual int createCharacter() = 0; //Pure virtual function
                Character();
                ~Character();   
};

#endif

---

//Character.cpp
#include "Character.h"
Character::Character()
{
//ctor
}

Character::~Character()
{
//dtor
}

---

//human.h
#ifndef HUMAN_H
#define HUMAN_H

#include "Character.h"

using namespace std;

class Human : public Character 
{
    private:
                int characterStrength;
                int characterDexterity;
                int characterIntelligence;
                string characterType;
                int characterTotal;

    public:
                Human();//Constructor 
                                ~Human();

                int getStrength ()
                {
                    cout << "Enter a number from 0 to 18\n";
                    cin >> characterStrength;

                    return characterStrength;
                }

                int getDexterity ()
                {
                    cout << "Enter a number from 0 to 18\n";
                    cin >> characterDexterity;

                    return characterDexterity;
                }

                int getIntelligence ()
                {
                    cout << "Enter a number from 0 to 18\n";
                    cin >> characterIntelligence;

                    return characterIntelligence;
                }

                string getType ()
                {
                    cout << "Please choose one of the following\n";
                    cout << "A -- Paladin \n";
                    cout << "B -- Ranger \n";
                    cout << "C -- Wizard \n";\
                    cin >> characterType;

                    return characterType;
                }

                virtual int createCharacter()
                {
                    characterTotal = characterStrength + characterIntelligence + characterDexterity;
                    return characterTotal;
                }
};

#endif

---

//Human.cpp
#include "Human.h"
Human::Human()
{
//ctor
}

Human::~Human()
{
//dtor
}

---

//orc.h
#ifndef ORC_H
#define ORC_H

#include "Character.h"

using namespace std;

class Orc : public Character
{
    private:
                int characterStrength;
                int characterDexterity;
                int characterIntelligence;
                int chaD;
                int chaI;
                int chaS;
                string characterClan;
                int characterTotal;

    public:
                Orc(); //Constructor
                        ~Orc();

                int getStrength()
                {
                    cout << "Enter a number between 0 to 18\n";
                    cin >> chaS;
                    characterStrength = chaS + 2;

                    return characterStrength;
                }

                int getDexterity()
                {
                    cout << "Enter a number between 0 to 18\n";
                    cin >> chaD;
                    characterDexterity = chaD - 2;

                    return characterDexterity;
                }

                int getIntelligence()
                {
                    cout << "Enter a number between 0 to 18\n";
                    cin >> chaI;
                    characterIntelligence = chaI - 2;

                    return characterIntelligence;
                }

                string getClan()
                {
                    cout << "Please choose one of the following\n";
                    cout << "A -- Barbarian \n";
                    cout << "B -- Berserker \n";
                    cout << "C -- Vanguard \n";\
                    cin >> characterClan;

                    return characterClan;
                }

                virtual int createCharacter()
                    {
                        characterTotal = characterStrength + characterIntelligence + characterDexterity;
                        return characterTotal;
                    }

};
#endif

---

//Orc.cpp
#include "Orc.h"
Orc::Orc()
{
//ctor
}

Orc::~Orc()
{
//dtor
}

Answer 1

您需要編譯所有源文件（而不是頭文件）並將它們鏈接在一起。 在這一點上， 最直接的方法是只在一個命令中指定所有文件名：

g++ maingame.cpp character.cpp human.cpp orc.cpp

大型項目通常會分別編譯每個文件，然后鏈接生成的.o （對象）文件，但是您似乎還沒有到此為止。

Answer 2

immibis提出了一點，但是我認為您應該花一些時間來研究makefile。 由於您似乎正在構建一個安靜的項目，因此每次手動編譯它都不舒服。 本教程是對makefile的很好的介紹。 從未停止學習！