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