:relfileprefix: ../../../
[#boost-urls-url_view_base-host_ipvfuture]

= xref:boost.adoc[pass:[boost]]::xref:boost/urls.adoc[pass:[urls]]::xref:boost/urls/url_view_base.adoc[pass:[url_view_base]]::host_ipvfuture


Return the host IPvFuture address


== Synopsis

Declared in header `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/url_view_base.hpp#L1288[boost/url/url_view_base.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
core::string_view
host_ipvfuture() const noexcept;
----

== Description


If the host type is
xref:boost/urls/host_type/ipvfuture.adoc[host_type::ipvfuture]
,        this function returns the address as
a string.
Otherwise, if the host type is not an
IPvFuture address, it returns an
empty string.

=== Example
[,cpp]
----
assert( url_view( "http://[v1fe.d:9]/index.htm" ).host_ipvfuture() == "v1fe.d:9" );
----

=== Complexity

Constant.

=== Exception Safety

Throws nothing.

=== BNF
[,cpp]
----
IPvFuture  = "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )
----

=== Specification

* link:https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2[3.2.2. Host (rfc3986)]