namespace boost{ namespace multiprecision{

class gmp_int;

typedef number<gmp_int >         mpz_int;

}} // namespaces

Class template gmp_int fulfils all of the requirements for a Backend type. Its members and non-member functions are deliberately not documented: these are considered implementation details that are subject to change.

The type of number_category<cpp_int<Args...> >::type is std::integral_constant<int, number_kind_integer>.

More information on this type can be found in the tutorial.