[#boost-urls-url_view_base-host_ipv6_address]
= xref:boost/urls/url_view_base/host_ipv6_address.adoc[boost::urls::url_view_base::host_ipv6_address]
:relfileprefix: ../../../
:mrdocs:

Return the host IPv6 address

== Synopsis

Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/url_view_base.hpp#L1308[boost/url/url_view_base.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/ipv6_address.adoc[ipv6_address]
host_ipv6_address() const noexcept;
----

== Description

If the host type is xref:boost/urls/host_type.adoc[`host_type::ipv6`], this function returns the address as a value of type xref:boost/urls/ipv6_address.adoc[`ipv6_address`]. Otherwise, if the host type is not an IPv6 address, it returns a default‐constructed value which is equal to the unspecified address "0:0:0:0:0:0:0:0".

== Example
[,cpp]
----
assert( url_view( "ftp://[::1]/" ).host_ipv6_address() == ipv6_address( "::1" ) );
----
== Complexity
Constant.

== Exception Safety
Throws nothing.

== BNF
[,cpp]
----
IPv6address =                            6( h16 ":" ) ls32
            /                       "::" 5( h16 ":" ) ls32
            / [               h16 ] "::" 4( h16 ":" ) ls32
            / [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
            / [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
            / [ *3( h16 ":" ) h16 ] "::"    h16 ":"   ls32
            / [ *4( h16 ":" ) h16 ] "::"              ls32
            / [ *5( h16 ":" ) h16 ] "::"              h16
            / [ *6( h16 ":" ) h16 ] "::"

ls32        = ( h16 ":" h16 ) / IPv4address
            ; least-significant 32 bits of address

h16         = 1*4HEXDIG
            ; 16 bits of address represented in hexadecimal
----
== Specification
* https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2[]

== Return Value

The IPv6 address as a value of type xref:boost/urls/ipv6_address.adoc[`ipv6_address`].


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