链接器错误:对`Reference_Genome：：seq[abi:cxx11 11]的未定义引用

Question

我对c和c++非常陌生，所以请尝试解释更具体的我应该做什么。该程序尝试使用多线程从目录中读取文件，并将这些信息存储在地图中，以便以后使用。

我一直在寻找类似的职位。不过，我想不出。

在https://github.com/kaldi-asr/kaldi/issues/938中，它说：“如果您收到关于未定义的符号引用的链接器错误，这些符号涉及std::__cxx11命名空间中的类型或标记abi:cxx11 11，那么它可能表明您试图将使用_GLIBCXX_USE_CXX11_ABI宏不同值编译的对象文件链接在一起。”

undefined reference to `pthread_cancel'的解决方案(添加"-pthread“标志)也不起作用。

我的代码是

#include <iostream>
#include <iomanip>
#include <fstream>
#include <vector>
#include <map>
#include <algorithm>
#include <random>
#include <unistd.h>
#include <cmath>
#include <stdlib.h>
#include <mutex>
#include <sys/wait.h>
#include <filesystem>
#include <string>
#include <pthread.h>

#define time_str(s) (s < 60 ? (to_string(s) + " second(s)") : (s < 3600 ? (to_string((s) / 60) + " minute(s)") : (to_string((s) / 3600) + " hour(s) and " + to_string(((s) % 3600) / 60) + " minute(s)")))
using namespace std;
namespace fs = std::filesystem;

struct MyGenom
{
    vector<string> filepaths;
    map<string, string> seq;
};

void check_rv(int rv) {
    if (rv != 0) {
        printf("Error: Value is %d\n", rv);
        exit(1);
    }
}

struct Reference_Genome {
    static long unsigned int idx;
    static map <string, string> seq;
    static pthread_mutex_t mtxLock;
    static vector <string> filepaths;

    static void writing(string path) {
 
    }

    static void *distribution(void *var) {
        
    }

    Reference_Genome(string dir, unsigned int n_threads) {
    
    }
};

int main(int argc, char const *argv[]) {
    string dir = "./data/ex_seq";
    unsigned int n_threads = 5;
    Reference_Genome ref(dir, n_threads);
    cout << "chr6: " << ref.seq["chr6"] << endl;
    cout << "chr9: " << ref.seq["chr9"] << endl;
    cout << "chr13: " << ref.seq["chr13"] << endl;
}

gcc版本是“线程模型: posix gcc版本9.3.0 (Ubuntu9.3.0-10ubuntu2)”。

错误是

testSeq.cpp:97: undefined reference to `Reference_Genome::seq[abi:cxx11]'
/usr/bin/ld: testSeq.cpp:98: undefined reference to `Reference_Genome::seq[abi:cxx11]'
/usr/bin/ld: testSeq.cpp:99: undefined reference to `Reference_Genome::seq[abi:cxx11]'
/usr/bin/ld: /tmp/cctfwVX2.o: in function `Reference_Genome::writing(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)':
/testSeq.cpp:46: undefined reference to `Reference_Genome::seq[abi:cxx11]'
/usr/bin/ld: testSeq.cpp:48: undefined reference to `Reference_Genome::seq[abi:cxx11]'
/usr/bin/ld: /tmp/cctfwVX2.o: in function `Reference_Genome::distribution(void*)':
testSeq.cpp:55: undefined reference to `Reference_Genome::filepaths[abi:cxx11]'
/usr/bin/ld: testSeq.cpp:55: undefined reference to `Reference_Genome::idx'
/usr/bin/ld: testSeq.cpp:56: undefined reference to `Reference_Genome::mtxLock'
/usr/bin/ld: testSeq.cpp:57: undefined reference to `Reference_Genome::idx'
/usr/bin/ld: testSeq.cpp:57: undefined reference to `Reference_Genome::filepaths[abi:cxx11]'
/usr/bin/ld: testSeq.cpp:58: undefined reference to `Reference_Genome::idx'
/usr/bin/ld: testSeq.cpp:58: undefined reference to `Reference_Genome::idx'
/usr/bin/ld: testSeq.cpp:59: undefined reference to `Reference_Genome::mtxLock'
/usr/bin/ld: /tmp/cctfwVX2.o: in function `Reference_Genome::Reference_Genome(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, unsigned int)':
testSeq.cpp:68: undefined reference to `Reference_Genome::filepaths[abi:cxx11]'
/usr/bin/ld: testSeq.cpp:70: undefined reference to `Reference_Genome::idx'
/usr/bin/ld: testSeq.cpp:72: undefined reference to `Reference_Genome::mtxLock'
/usr/bin/ld: testSeq.cpp:85: undefined reference to `Reference_Genome::mtxLock'
/usr/bin/ld: testSeq.cpp:88: undefined reference to `Reference_Genome::filepaths[abi:cxx11]'
collect2: error: ld returned 1 exit status

Answer 1

当您在类中声明静态变量时，还必须在类之外声明它一次。在本例中，您可以将其放在C++文件的底部或main()函数与class Reference_Genome定义之间：

long unsigned int Reference_Genome::idx;
map <string, string> Reference_Genome::seq;
pthread_mutex_t Reference_Genome::mtxLock;
vector <string> Reference_Genome::filepaths;

其思想是您可以将类定义放入一个头文件中，包含在多个不同的编译单元中，但是静态变量只定义一次，即在您选择的一个.cpp文件中。