Return the host
<include/boost/url/authority_view.hpp>
template<class StringToken = string_token::return_string>
StringToken::result_type
host(StringToken&& token) const;
This function returns the host portion of the authority as a string, or the empty string if there is no authority. Any percent-escapes in the string are decoded first.
assert( url_view( "https://www%2droot.example.com/" ).host() == "www-root.example.com" );
host = IP-literal / IPv4address / reg-name
IP-literal = "[" ( IPv6address / IPvFuture ) "]"
reg-name = *( unreserved / pct-encoded / "-" / ".")