:relfileprefix: ../../../
[#C4CA22E0A99B02694AC3992AD110FECF76610EE3]

= Function authority_view::host_ipv6_address

pass:v,q[Return the host IPv6 address]


== Synopsis

Declared in header `</boost/url/authority_view.hpp#L943[boost/url/authority_view.hpp,window=blank_]>`

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

== Description

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

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

=== Complexity
pass:v,q[Constant.]

=== Exception Safety
pass:v,q[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

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



== Return Value

* `ipv6_address` 




