c++ - CMAKE LINKING ERROR 与用户定义的共享库

Question

我是 cmake 世界的新手。当我在 C++ 中试验一些基本的 cmake 配置时，出现了这个问题。准确地说，以下是我的目录结构:

/源----

 |-> CMakeLists.txt
   |-> main.cpp
   |-> lib----
              |-> libfsystem.so
   |->filesystem----
                    |->CMakeLists.txt
                    |->listfiles.cpp
                    |->include-----
                                   |->fsystem.h

现在，/src/filesystem/CMakeLists.txt 文件是这样的

cmake_minimum_required(VERSION 2.8)
project(fsystem)
set(CMAKE_BUILD_TYPE Release)
link_directories(${CMAKE_CURRENT_SOURCE_DIR}/build)
find_package(Boost REQUIRED system filesystem)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/../lib)
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
add_library(fsystem SHARED listfiles.cpp)

而/src/CMakeLists.txt文件是这样的

cmake_minimum_required(VERSION 2.8)

project(vessel_detect)

add_subdirectory(filesystem)

add_executable(main main.cpp)

set(CMAKE_LIBRARY_PATH ${CMAKE_CURRENT_SOURCE_DIR}/lib)
find_library(libpath fsystem)
MESSAGE(${libpath})
target_link_libraries(main ${libpath})

1. 库 libfsystem.so 已成功创建。
2. 库 libfsystem.so 也被/src/CMakeLists.txt 成功找到

然而，当 main.cpp 的链接完成后，它会给我几个 undefined reference 错误，这些错误不应该发生，因为所有内容都已经定义好了。为了更完整，以下是 main.cpp 文件的内容

main.cpp

#include<iostream>
#include"filesystem/include/fsystem.h"
using namespace std;
int main(void)
{
        string path ("~");
        vector<string>* output;
        output = listfiles(path);
        return 0;
}

listfiles.cpp的内容是

listfiles.cpp

#include"fsystem.h"
using namespace boost::filesystem;
vector<string>* listfiles(int argc, char* argv[])
{
         if (argc<2)
        {
                std::cout<<"No file name provided"<<std::endl;
        }
        else
        {
                path p(argv[1]);
                vector<string>* output;
                if (exists(p))
                {
                        if(is_directory(p))
                        {
                                std::cout<<"You specified a directory"<<std::endl;
                                std::cout<<"Its contents are as follows :-"<<std::endl;
                                typedef std::vector<path> vec;
                                vec v;
                                copy(directory_iterator(p),directory_iterator(),back_inserter(v));
                                sort(v.begin(),v.end());
                                for(vec::const_iterator it(v.begin());it!=v.end();++it)
                                          output->push_back(it->filename().string());
//                                        std::cout<<it->filename()<<std::endl;
                        }
                        else if (is_regular_file(p))
                                {
                                        std::cout<<argv[1]<<"   "<<file_size(p)<<std::endl;
                                }
                                else
                                {
                                        std::cout<<"The file is neither a directory nor a regular file"<<std::endl;
                                }
                }
                else
                {
                        std::cout<<"The speicified path does not exist"<<std::endl;
                                                                                                             }             
           }
}

最后，fsystem.h 的内容是:

fsystem.h

#ifndef _fsystem_h
#define _fsystem_h
#include<iostream>
#include<string>
#include<vector>
#include"boost/filesystem.hpp"
using namespace std;
vector<string>* listfiles(string);
#endif

有人可以为我在链接 main.cpp 期间遇到的 undefined reference 错误提供原因吗？如果您能为我提供此问题的解决方案，我将不胜感激。

谢谢

Answer 1

您没有链接提升。您需要将 target_link_libraries(fsystem ${Boost_LIBRARIES}) 添加到/src/filesystem/CMakeLists.txt 的末尾，并在 find_package 和添加_库。

cmake_minimum_required(VERSION 2.8)
project(fsystem)
set(CMAKE_BUILD_TYPE Release)
link_directories(${CMAKE_CURRENT_SOURCE_DIR}/build)
find_package(Boost REQUIRED system filesystem)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/../lib)
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
include_directories(${Boost_INCLUDE_DIRS})
add_library(fsystem SHARED listfiles.cpp)
target_link_libraries(fsystem ${Boost_LIBRARIES})