c++ 未定义对 vtable 的引用 [英] c++ undefined reference to vtable

问题描述

我正在学习 C++.我正在尝试做一个练习，我用一个函数定义一个纯虚拟类的几个实现.我在链接使用这些实现的类时遇到问题.

I'm learning C++. I'm trying to do an exercise where I define several implementations of a pure virtual class with a single function. I'm having trouble linking the class that uses these implementations.

==> BasicMath.h <==
#ifndef BASIC_MATH_H
#define BASIC_MATH_H

#include<string>
#include<vector>    

class BasicMath { };


#endif // BASIC_MATH_H

==> Operation.h <==

#ifndef OPERATION
#define OPERATION

#include<string>
#include<vector>    

class Operation {
 public:
  virtual void perform(std::vector<std::string> vec) = 0;
};


#endif // OPERATION

==> Sum.h <==
#ifndef SUM_H
#define SUM_H

#include "Operation.h"

class Sum: public Operation {
 public:
  void perform(std::vector<std::string> vec);
};

#endif // SUM_H

==> BasicMath.cpp <==
#ifndef BASIC_MATH_C
#define BASIC_MATH_C

#include <string>
#include <vector>
#include <iostream>
#include "BasicMath.h"
#include "Sum.h"

int main(int argc, char* argv[]) {
  Sum op;
}

#endif // BASIC_MATH_C

==> Sum.cpp <==
#ifndef SUM_C
#define SUM_C

#include <vector>
#include <string>
#include <iostream>
#include "Sum.h"

void Sum::perform(std::vector<std::string> vec) {
    using namespace std;
    int total = 0;
    cout << "Total: " << total << "
";
};

#endif // SUM_C

编译:

$ g++ -c Sum.cpp
$ g++ -o BasicMath BasicMath.cpp
/tmp/cc1VXjNl.o:BasicMath.cpp:(.text$_ZN3SumC1Ev[Sum::Sum()]+0x16): undefined reference to `vtable for Sum'
collect2: ld returned 1 exit status

我 95% 确定我在这里至少做了一件愚蠢的事情 - 但我的大脑拒绝告诉我是什么.

I'm 95% sure I'm doing at least one foolish thing here - but my brain is refusing to tell me what.

我看到 this 问题，但未能解决我的问题.

I have see this question but have not managed to fix my issue.

推荐答案

您没有在编译和链接行中包含 Sum.o 目标文件(第二次使用 g++).

You're not including the Sum.o object file on your compile&link line (second g++ use).

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