21 Internet protocol [internet]

21.5 Class ip::address_v4 [internet.address.v4]

21.5.1 Struct ip::address_v4::bytes_type [internet.address.v4.bytes]

namespace std {
namespace experimental {
namespace net {
inline namespace v1 {
namespace ip {

  struct address_v4::bytes_type : array<unsigned char, 4>
  {
    template<class... T> explicit constexpr bytes_type(T... t)
      : array<unsigned char, 4>{{static_cast<unsigned char>(t)...}} {}
  };

} // namespace ip
} // inline namespace v1
} // namespace net
} // namespace experimental
} // namespace std
1

The ip::address_v4::bytes_type type is a standard-layout struct that provides a byte-level representation of an IPv4 address in network byte order.