C++ 使用接口时对vtable的未定义引用

我环顾四周，不知道哪里出了问题，因为我在使用接口时似乎遵循了正确的惯例，但也许我忽略了一些东西。我得到的确切错误是：

对“Icommand的vtable”的未定义引用

我刚刚开始将我的类和类声明分离到单独的头文件中，所以我可能在某个地方丢失了一个预处理器指令

main.cpp:

#include <iostream>
#include <string>
#include <cstdlib>
#include "Icommand.h"

#include "Command.h"

using namespace std;

void pause();

int main(){


    Icommand *run = new Command("TEST");
    cout << run->getCommand() << endl;
    delete run;

    pause();
}

void pause(){
    cin.clear();
    cin.ignore(cin.rdbuf()->in_avail());
    cin.get();
}

#ifndef ICOMMAND_H
#define ICOMMAND_H

#include <string>
#include <vector>


class Icommand
{
    private:

    public:
        Icommand(){}
        virtual ~Icommand(){}
        virtual bool run(std::string object1) = 0;
        virtual bool run(std::string object1, std::string object2) = 0;
        virtual std::string getCommand() const;
};



#endif // ICOMMAND_H

#ifndef COMMAND_H
#define COMMAND_H

#include <string>
#include <vector>

#include "Icommand.h"

class Command : public Icommand {

    private:
        std::string command;
        std::vector<std::string> synonymns;
        Command(); // private so class much be instantiated with a command

    public:
        Command(std::string command) : command(command){}
        ~Command(){}
        bool run(std::string object1);
        bool run(std::string object1, std::string object2);
        std::string getCommand() const;


};
#endif // COMMAND_H

#include <string>
#include <vector>

#include "Command.h"

bool Command::run(std::string object1){
    return false;
}
bool Command::run(std::string object1, std::string object2){
    return false;
}
std::string Command::getCommand() const {return command;}

#包括
#包括
#包括
#包括“Icommand.h”
#包括“Command.h”
使用名称空间std；
无效暂停（）；
int main（）{
Icommand*run=新命令（“测试”）；
cout getCommand（）在_avail（）中；
cin.get（）；
}

Icommand.h:

#include <iostream>
#include <string>
#include <cstdlib>
#include "Icommand.h"

#include "Command.h"

using namespace std;

void pause();

int main(){


    Icommand *run = new Command("TEST");
    cout << run->getCommand() << endl;
    delete run;

    pause();
}

void pause(){
    cin.clear();
    cin.ignore(cin.rdbuf()->in_avail());
    cin.get();
}

#ifndef ICOMMAND_H
#define ICOMMAND_H

#include <string>
#include <vector>


class Icommand
{
    private:

    public:
        Icommand(){}
        virtual ~Icommand(){}
        virtual bool run(std::string object1) = 0;
        virtual bool run(std::string object1, std::string object2) = 0;
        virtual std::string getCommand() const;
};



#endif // ICOMMAND_H

#ifndef COMMAND_H
#define COMMAND_H

#include <string>
#include <vector>

#include "Icommand.h"

class Command : public Icommand {

    private:
        std::string command;
        std::vector<std::string> synonymns;
        Command(); // private so class much be instantiated with a command

    public:
        Command(std::string command) : command(command){}
        ~Command(){}
        bool run(std::string object1);
        bool run(std::string object1, std::string object2);
        std::string getCommand() const;


};
#endif // COMMAND_H

#include <string>
#include <vector>

#include "Command.h"

bool Command::run(std::string object1){
    return false;
}
bool Command::run(std::string object1, std::string object2){
    return false;
}
std::string Command::getCommand() const {return command;}

\ifndef ICOMMAND\u H
#定义ICOMMAND_H
#包括
#包括
类I命令
{
私人：
公众：
Icommand（）{}
虚拟~Icommand（）{}
虚拟bool运行（std:：string object1）=0；
虚拟bool运行（std:：string object1，std:：string object2）=0；
虚拟std:：string getCommand（）常量；
};
#endif//ICOMMAND\u H

Command.h:

#include <iostream>
#include <string>
#include <cstdlib>
#include "Icommand.h"

#include "Command.h"

using namespace std;

void pause();

int main(){


    Icommand *run = new Command("TEST");
    cout << run->getCommand() << endl;
    delete run;

    pause();
}

void pause(){
    cin.clear();
    cin.ignore(cin.rdbuf()->in_avail());
    cin.get();
}

#ifndef ICOMMAND_H
#define ICOMMAND_H

#include <string>
#include <vector>


class Icommand
{
    private:

    public:
        Icommand(){}
        virtual ~Icommand(){}
        virtual bool run(std::string object1) = 0;
        virtual bool run(std::string object1, std::string object2) = 0;
        virtual std::string getCommand() const;
};



#endif // ICOMMAND_H

#ifndef COMMAND_H
#define COMMAND_H

#include <string>
#include <vector>

#include "Icommand.h"

class Command : public Icommand {

    private:
        std::string command;
        std::vector<std::string> synonymns;
        Command(); // private so class much be instantiated with a command

    public:
        Command(std::string command) : command(command){}
        ~Command(){}
        bool run(std::string object1);
        bool run(std::string object1, std::string object2);
        std::string getCommand() const;


};
#endif // COMMAND_H

#include <string>
#include <vector>

#include "Command.h"

bool Command::run(std::string object1){
    return false;
}
bool Command::run(std::string object1, std::string object2){
    return false;
}
std::string Command::getCommand() const {return command;}

#ifndef命令
#定义命令
#包括
#包括
#包括“Icommand.h”
类命令：公共Icommand{
私人：
std:：string命令；
向量同义词；
Command（）；//私有类可以用命令实例化
公众：
命令（std:：string命令）：命令（Command）{}
~Command（）{}
bool运行（std:：string object1）；
bool运行（std:：string object1，std:：string object2）；
std:：string getCommand（）常量；
};
#endif//COMMAND\u H

Command.cpp:

#include <iostream>
#include <string>
#include <cstdlib>
#include "Icommand.h"

#include "Command.h"

using namespace std;

void pause();

int main(){


    Icommand *run = new Command("TEST");
    cout << run->getCommand() << endl;
    delete run;

    pause();
}

void pause(){
    cin.clear();
    cin.ignore(cin.rdbuf()->in_avail());
    cin.get();
}

#ifndef ICOMMAND_H
#define ICOMMAND_H

#include <string>
#include <vector>


class Icommand
{
    private:

    public:
        Icommand(){}
        virtual ~Icommand(){}
        virtual bool run(std::string object1) = 0;
        virtual bool run(std::string object1, std::string object2) = 0;
        virtual std::string getCommand() const;
};



#endif // ICOMMAND_H

#ifndef COMMAND_H
#define COMMAND_H

#include <string>
#include <vector>

#include "Icommand.h"

class Command : public Icommand {

    private:
        std::string command;
        std::vector<std::string> synonymns;
        Command(); // private so class much be instantiated with a command

    public:
        Command(std::string command) : command(command){}
        ~Command(){}
        bool run(std::string object1);
        bool run(std::string object1, std::string object2);
        std::string getCommand() const;


};
#endif // COMMAND_H

#include <string>
#include <vector>

#include "Command.h"

bool Command::run(std::string object1){
    return false;
}
bool Command::run(std::string object1, std::string object2){
    return false;
}
std::string Command::getCommand() const {return command;}

#包括
#包括
#包括“Command.h”
bool命令：：run（std：：string object1）{
返回false；
}
bool命令：：run（std：：string object1，std：：string object2）{
返回false；
}
std:：string命令：：getCommand（）常量{return Command；}

在Icommand.h中，更换

virtual std::string getCommand() const;

与

---

使其纯粹虚拟化。然后编译器可以为

Icommand

生成vtable。或者，实现

Icommand:：getCommand

您需要

virtual~Command（）{}

是的，这已经解决了问题，尽管我仍然难以理解为什么它需要一个纯虚拟函数。我必须熟悉vtables。