Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is an older version of Boost and was released in 2021. The current version is 1.89.0.

ip::address_v4::is_class_b

(Deprecated: Use ip::network_v4 class.) Determine whether the address is a class B address.

bool is_class_b() const;