std::experimental::filesystem::recursive_directory_iterator::depth
From cppreference.com
                    
                                        
                    
                    
                                                            
                    | int depth() const; | (filesystem TS) | |
Returns the number of directories from the starting directory to the currently iterated directory, i.e. the current depth of the directory hierarchy.
The starting directory has depth of 0.
[edit] Parameters
(none)
[edit] Return value
Current depth of the directory hierarchy.
[edit] Exceptions
(none)