C++ 17 文件系统 copy_file 访问被拒绝

Question

I'm using visual studio 2017, running with the c++17 ISO Standard(not boost) set to be able to use <filesystem> . I'm running into a wall though because everytime I run, whether in debug or release, file_copy() gives me the error access denied. I've checked the other bits of my code and the only thing that isn't working is file_copy() . Does anyone know why I'm getting this error and how to fix it? I'm the administrative account on my PC.

std::vector<std::string> findAndCopyFiles()
{
    std::vector<std::string> fileNames;
    std::error_code errCode;
    errCode.clear();

    fs::current_path("C:\\Users\\kenny\\Desktop\\Engine", errCode);
    std::cout << errCode.message() << std::endl; errCode.clear();

    fs::path pa = fs::current_path();
    pa += "\\TEMP";
    std::cout << pa.string() << std::endl;

    if (fs::create_directory(pa, errCode))//Create directory for copying all files)
    {
        std::cout << "Directory created successfully" << std::endl;
        std::cout << errCode.message() << std::endl; errCode.clear();
    }
    fs::path tempDir(pa);
    fs::path currentDirectory = fs::current_path();
    fs::recursive_directory_iterator dirIter(currentDirectory);
    for (auto &p : dirIter)
    {
        if (p.path().extension() == ".cpp" || p.path().extension() == ".h")
        {
            //std::string fileContents = getFileContents(p.path().string());

            std::string fileName = p.path().stem().string();
            if (!fs::copy_file(p.path(), tempDir, fs::copy_options::overwrite_existing, errCode))
            {
                std::cout << "failed to copy file: " << fileName << " from " << p.path().string() << " to " << tempDir.string() <<std::endl;
            }
            std::cout << errCode.message() << std::endl; errCode.clear();

            //ensures file is a cpp file before adding it to list of fileNames
            if (p.path().extension().string() == ".cpp")
            {
                auto it = std::find(fileNames.begin(), fileNames.end(), fileName); //seaches TEMP folder for file
                if (it == fileNames.end())
                {//if file was not found in vector of registered file names, add it
                    fileNames.push_back(fileName);
                }
            }
        }
    }
    std::cout << "All files found. " << fileNames.size() << " files were found" << std::endl;
    return fileNames;
}

Answer 1

As per the comments. You were trying to overwrite a directory with a regular file. From the documentation [trimmed]

o Otherwise, if the destination file already exists...
  o Report an error if any of the following is true:
    o to and from are the same as determined by equivalent(from, to);
    o to is not a regular file as determined by !is_regular_file(to)

So you need to append the filename to the destination directory path using the `std::filesystem::operator/ overload (untested)...

if (!fs::copy_file(p.path(), tempDir / p.filename(), fs::copy_options::overwrite_existing, errCode))