std::ctype<CharT>::~ctype (3) - Linux Man Pages
Defined in header <locale>
Destructs a std::ctype facet. This destructor is protected and virtual (due to base_class destructor being virtual). An object of type std::ctype, like most facets, can only be destroyed when the last std::locale object that implements this facet goes out of scope or if a user-defined class is derived from std::ctype and implements a public destructor.
// Run this code