[#boost-urls-ipv6_address-2constructor-08]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/ipv6_address.adoc[ipv6&lowbar;address]::ipv6&lowbar;address
:relfileprefix: ../../../
:mrdocs:

Construct from an IPv4 address&period;

== Synopsis

Declared in `&lt;https://www.github.com/boostorg/url/blob/develop/include/boost/url/ipv6_address.hpp#L141[boost&sol;url&sol;ipv6&lowbar;address&period;hpp]&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
ipv6&lowbar;address(xref:boost/urls/ipv4_address.adoc[ipv4&lowbar;address] const& addr) noexcept;
----

== Description

This function constructs an IPv6 address from the IPv4 address `addr`&period; The resulting address is an IPv4&hyphen;Mapped IPv6 Address&period;

== Specification

* https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.5.2[2&period;5&period;5&period;2&period; IPv4&hyphen;Mapped IPv6 Address (rfc4291)]

== Parameters

[cols=2]
|===
| Name
| Description
| *addr*
| The address to construct from&period;
|===


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