:relfileprefix: ../../../
[#boost-urls-ipv6_address-2constructor-08]

= xref:boost.adoc[pass:[boost]]::xref:boost/urls.adoc[pass:[urls]]::xref:boost/urls/ipv6_address.adoc[pass:[ipv6_address]]::ipv6_address


Construct from an IPv4 address.


== Synopsis

Declared in header `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/ipv6_address.hpp#L141[boost/url/ipv6_address.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
ipv6_address(xref:boost/urls/ipv4_address.adoc[ipv4_address] const& addr) noexcept;
----

== Description


This function constructs an IPv6 address
from the IPv4 address `addr`. The resulting
address is an IPv4-Mapped IPv6 Address.

=== Specification

* link:https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.5.2[2.5.5.2. IPv4-Mapped IPv6 Address (rfc4291)]





== Parameters

|===
| Name | Description 

| *addr*
| 
The address to construct from.

|===