std::basic_regex<CharT,Traits>::flags
From cppreference.com
                    
                                        
                    < cpp | regex | basic regex
                    
                                                            
                    | flag_type flags() const; | (since C++11) | |
Returns the regular expression syntax flags as set in the constructor or the last call to assign().
Parameters
(none)
Return value
Current regular expression syntax flags.
Exceptions
(none)
Example
| This section is incomplete Reason: no example |