std::ctype<CharT>::ctype
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header  <locale>
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|   explicit ctype( std::size_t refs = 0 );  | 
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Creates a std::ctype facet and forwards the starting reference count refs to the base class constructor, locale::facet::facet()
Parameters
| refs | - | starting reference count |