How to get a list of files in a folder in which the files are sorted with modified date time?

Question

I need to a list of files in a folder and the files are sorted with their modified date time.

I am working with C++ under Linux, the Boost library is supported.

Answer 1

Most operating systems do not return directory entries in any particular order. If you want to sort them (you probably should if you are going to show the results to a human user), you need to do that in a separate pass. One way you could do that is to insert the entries into a std::multimap, something like so:

namespace fs = boost::filesystem;
fs::path someDir("/path/to/somewhere");
fs::directory_iterator end_iter;

typedef std::multimap<std::time_t, fs::path> result_set_t;
result_set_t result_set;

if ( fs::exists(someDir) && fs::is_directory(someDir))
{
  for( fs::directory_iterator dir_iter(someDir) ; dir_iter != end_iter ; ++dir_iter)
  {
    if (fs::is_regular_file(dir_iter->status()) )
    {
      result_set.insert(result_set_t::value_type(fs::last_write_time(dir_iter->path()), *dir_iter));
    }
  }
}

You can then iterate through result_set, and the mapped boost::filesystem::path entries will be in ascending order.