Walking directories with directory_iterator

A fs::directory_iterator is just what it says on the tin. An object of this type lets you walk the contents of a single directory, entry by entry:

    fs::path p = fs::current_path();
      // List the current directory.
    for (fs::directory_entry entry : fs::directory_iterator(p)) {
      std::cout << entry.path().string() << ": "
      << entry.file_size() << " bytes\n";
    }

Incidentally, notice the use of entry.path().string() in the preceding code. This is required, because operator<< acts extremely bizarrely on path objects--it always outputs as if you'd written std::quoted(path.string()). If you want the path itself, with no extra quotes, you always have to convert to std::string before outputting. (Similarly, std::cin >> path won't work to get a path from the user, but that's less obnoxious, since you should never use operator>> anyway. See Chapters 9, Iostreams, and Chapter 10, Regular Expressions...