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 2019. The current version is 1.89.0.

ip::address_v4::netmask

ip::address_v4::netmask

(Deprecated: Use ip::network_v4 class.) Obtain the netmask that corresponds to the address, based on its address class.

static address_v4 netmask(
    const address_v4 & addr);