[#boost-urls-url-set_host_ipv4]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/url.adoc[url]::set&lowbar;host&lowbar;ipv4
:relfileprefix: ../../../
:mrdocs:

Set the host to an address

== Synopsis

Declared in `&lt;https://www.github.com/boostorg/url/blob/develop/include/boost/url/url.hpp#L450[boost&sol;url&sol;url&period;hpp]&gt;`

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

== Description

The host is set to the specified IPv4 address&period; The host type is xref:boost/urls/host_type.adoc[`host&lowbar;type&colon;&colon;ipv4`]&period;

== Example
[,cpp]
----
assert( url("http://www.example.com").set_host_ipv4( ipv4_address( "127.0.0.1" ) ).buffer() == "http://127.0.0.1" );
----
== Complexity
Linear in `this&hyphen;&gt;size()`&period;

== Postconditions
[,cpp]
----
this->has_authority() == true && this->host_ipv4_address() == addr && this->host_type() == host_type::ipv4
----
== Exception Safety
Strong guarantee&period; Calls to allocate may throw&period;

== BNF
[,cpp]
----
IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet

dec-octet   = DIGIT                 ; 0-9
            / %x31-39 DIGIT         ; 10-99
            / "1" 2DIGIT            ; 100-199
            / "2" %x30-34 DIGIT     ; 200-249
            / "25" %x30-35          ; 250-255
----
== Specification
* https://en.wikipedia.org/wiki/IPv4[]
* https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2[]

== Return Value

`&ast;this`

== Parameters

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

== See Also

xref:boost/urls/url/set_encoded_host.adoc[`set&lowbar;encoded&lowbar;host`], xref:boost/urls/url/set_encoded_host_address.adoc[`set&lowbar;encoded&lowbar;host&lowbar;address`], xref:boost/urls/url/set_encoded_host_name.adoc[`set&lowbar;encoded&lowbar;host&lowbar;name`], xref:boost/urls/url/set_host.adoc[`set&lowbar;host`], xref:boost/urls/url/set_host_address.adoc[`set&lowbar;host&lowbar;address`], xref:boost/urls/url/set_host_ipv6.adoc[`set&lowbar;host&lowbar;ipv6`], xref:boost/urls/url/set_host_ipvfuture.adoc[`set&lowbar;host&lowbar;ipvfuture`], xref:boost/urls/url/set_host_name.adoc[`set&lowbar;host&lowbar;name`]&period;


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