Question

我正在研究boost序列化，并且编写了以下代码，该序列化了B类的对象，而该序列又序列化了A类的对象。

当我尝试将代码拆分为多个文件，分别将两个类的声明和实现分开时，出现以下链接器错误。

make -k 
g++ -std=c++11 main.cpp a.cpp b.cpp -lboost_serialization -lboost_filesystem -lboost_system
Undefined symbols for architecture x86_64:
  "void B::serialize<boost::archive::binary_iarchive>(boost::archive::binary_iarchive&, unsigned int)", referenced from:
      void boost::serialization::access::serialize<boost::archive::binary_iarchive, B>(boost::archive::binary_iarchive&, B&, unsigned int) in main-5e4da5.o
  "void B::serialize<boost::archive::binary_oarchive>(boost::archive::binary_oarchive&, unsigned int)", referenced from:
      void boost::serialization::access::serialize<boost::archive::binary_oarchive, B>(boost::archive::binary_oarchive&, B&, unsigned int) in main-5e4da5.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [build] Error 1

我设法通过添加一些额外的代码来解决链接器错误，但是在程序打印“保存”之后，我又遇到了段错误。怎么了？

有效的代码，1个文件

main.cpp

// g++ -std=c++11 main.cpp a.cpp b.cpp -lboost_serialization -lboost_filesystem -lboost_system
#include <iostream>
#include <fstream>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/filesystem.hpp>

class A {
public:
    int num;
    template<class Archive>
    void serialize(Archive & ar, unsigned int version)
    {
        ar & num;
    }
};

class B {
public:
    A a;
    template<class Archive>
    void serialize(Archive & ar, unsigned int version)
    {
        ar & a;
    }
};

int main(int argc, char * argv[]) {
    B b;
    if(!boost::filesystem::exists("saved")) {
        b.a.num = 15;
        std::ofstream out("saved");
        boost::archive::binary_oarchive oa(out);
        oa << b;
        out.close();
    } else {
        std::ifstream in("saved");
        boost::archive::binary_iarchive ia(in);
        ia >> b;
        in.close();
    }
    std::cout << b.a.num << "\n";
    return 0;
}

无效的代码，最多5个文件

main.cpp

// g++ -std=c++11 main.cpp a.cpp b.cpp -lboost_serialization -lboost_filesystem -lboost_system
#include <iostream>
#include <fstream>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/filesystem.hpp>

#include "b.hpp"

int main(int argc, char * argv[]) {
    B b;
    if(!boost::filesystem::exists("saved")) {
        b.a.num = 15;
        std::cout << "saving\n";
        std::ofstream out("saved", std::ios::binary);
        boost::archive::binary_oarchive oa(out);
        oa << b;
        out.close();
        std::cout << "saved\n";
    } else {
        std::cout << "loading\n";
        std::ifstream in("saved", std::ios::binary);
        boost::archive::binary_iarchive ia(in);
        ia >> b;
        in.close();
        std::cout << "loaded\n";
    }
    std::cout << b.a.num << "\n";
    return 0;
}

b.hpp

#ifndef B_H
#define B_H

#include "a.hpp"

class B {
public:
    A a;
    template<class Archive>
    void serialize(Archive & ar, unsigned int version);
};

/*
// without the following code I get a linking error, but anyway, the code leads to a crash
namespace boost
{
    namespace serialization
    {
        template<class Archive>
        void serialize(Archive & ar, B & b, unsigned int version)
        {
            ar & b;
        }
    }
}
*/

#endif // B_H

b.cpp

#include "b.hpp"

#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>

template<class Archive>
void B::serialize(Archive & ar, unsigned int version)
{
    ar & a;
}

a.hpp

#ifndef A_H
#define A_H

class A {
public:
    int num;
    template<class Archive>
    void serialize(Archive & ar, unsigned int version);

};

#endif // A_H

a.cpp

#include "a.hpp"

#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>

template<class Archive>
void A::serialize(Archive & ar, unsigned int version)
{
    ar & num;
}

在多个文件上分割相同代码时，为什么Boost序列化会给我一个链接错误（然后是segfault）？

0 个答案: