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

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


Return the IPv6 Zone ID


== Synopsis

Declared in header `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/url_view_base.hpp#L1450[boost/url/url_view_base.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
xref:boost/urls/pct_string_view.adoc[pct_string_view]
encoded_zone_id() const noexcept;
----

== Description


If the host type is
xref:boost/urls/host_type/ipv6.adoc[host_type::ipv6]
,        this function returns the Zone ID as
a string. Otherwise an empty string is returned.
The returned string may contain
percent escapes.

=== Example
[,cpp]
----
assert( url_view( "http://[fe80::1%25eth0]/" ).encoded_zone_id() == "eth0" );
----

=== Complexity

Constant.

=== Exception Safety

Throws nothing.

=== BNF
[,cpp]
----
host        = IP-literal / IPv4address / reg-name

IP-literal = "[" ( IPv6address / IPv6addrz / IPvFuture  ) "]"

ZoneID = 1*( unreserved / pct-encoded )

IPv6addrz = IPv6address "%25" ZoneID
----

=== Specification

* link:https://datatracker.ietf.org/doc/html/rfc6874[Representing IPv6 Zone Identifiers in Address Literals and Uniform Resource Identifiers]