Scan folders with non English letters in a given directory

Question

here is a function written in c++ 2011 (VS); I'm using this function to get the extension and the size of every file in every directory. My problem is when there is a folder named something in non English letters, it won't open that folder to search for extensions. I would appreciate if anyone could help me with this issue.

void scan(path const& f)
{
    directory_iterator d(f);
    directory_iterator e;
    for (; d != e; ++d)


    {
            string ext = d->path().extension();
            _ULonglong size = file_size(d->path());
            if (is_directory(d->status())) 
                scan(d->path());
    }

}