包含<experimental filesystem =“”>后未声明'std :: filesystem'

时间:2019-04-02 12:22:04

标签: c++ cmake c++17

我检查了有关c ++ 17下文件系统链接的很多问题,但仍然无法成功建立链接。我的main.cpp文件如下。

#include <experimental/filesystem>


int main(int argc, char** argv)
{
    std::string imageDirectory = "./image";;
    std::vector<std::string> imagePath;

    for (const auto& entry: std::filesystem::directory_iterator(imageDirectory))
    {
        imagePath.push_back(entry.path());
        std::cout << entry.path() << std::endl;
    }

    return 0;
}

我的CMakeLists.txt如下。

cmake_minimum_required(VERSION 3.8 FATAL_ERROR)

project(visual_hull LANGUAGES CXX)
set(CMAKE_CXX_STANDARD 17)
add_library(dataIO
        STATIC
            dataIO.hpp
            dataIO.cpp)

find_package(OpenCV REQUIRED core highgui imgproc)

target_link_libraries(dataIO ${OpenCV_LIBS})

add_executable(visual_hull main.cpp)

target_link_libraries(visual_hull PUBLIC dataIO
                                         stdc++fs)

错误如下。

/home/SENSETIME/zhangshunkang/Downloads/programming/c++/visual_hull/main.cpp: In function ‘int main(int, char**)’:
/home/SENSETIME/zhangshunkang/Downloads/programming/c++/visual_hull/main.cpp:15:31: error: ‘std::filesystem’ has not been declared
  for (const auto& entry: std::filesystem::directory_iterator(imageDirectory))
                               ^
CMakeFiles/visual_hull.dir/build.make:62: recipe for target 'CMakeFiles/visual_hull.dir/main.cpp.o' failed
make[2]: *** [CMakeFiles/visual_hull.dir/main.cpp.o] Error 1
CMakeFiles/Makefile2:72: recipe for target 'CMakeFiles/visual_hull.dir/all' failed
make[1]: *** [CMakeFiles/visual_hull.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2

2 个答案:

答案 0 :(得分:4)

似乎您的C ++ 17编译器不包含标准的filesystem标头。解决该问题的一种可能方法:

#ifndef __has_include
  static_assert(false, "__has_include not supported");
#else
#  if __has_include(<filesystem>)
#    include <filesystem>
     namespace fs = std::filesystem;
#  elif __has_include(<experimental/filesystem>)
#    include <experimental/filesystem>
     namespace fs = std::experimental::filesystem;
#  elif __has_include(<boost/filesystem.hpp>)
#    include <boost/filesystem.hpp>
     namespace fs = boost::filesystem;
#  endif
#endif

然后在各处使用fs::而不是std::filesystem::

答案 1 :(得分:2)

您使用std::filesystem::directory_iteratorstd::filesystem::directory_iterator和整个命名空间std::filesystem在标头<filesystem>中声明。

您尚未包含标题<filesystem>。相反,您包括了<experimental/filesystem>。该标头未​​声明std::filesystem::directory_iterator。而是声明std::experimental::filesystem::directory_iterator

您可以始终使用技术规范中的标准文件系统库或实验性文件系统库,但不能将它们混合在一起。如果您的目标是C ++ 17,则应使用<filesystem>

  

我将收到文件系统错误:没有这样的文件或目录

理想的解决方案是将编译器升级到对C ++ 17具有非实验性支持的版本。否则,请使用实验性TS或Boost。