[#boost-urls-static_url-set_host_ipv4]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/static_url.adoc[static&lowbar;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/static_url.hpp#L382[boost&sol;url&sol;static&lowbar;url&period;hpp]&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/static_url.adoc[static&lowbar;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

* link:https://en.wikipedia.org/wiki/IPv4[IPv4 (Wikipedia)]
        
* link:https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2[            3&period;2&period;2&period; Host (rfc3986)]



== Parameters


|===
| Name | Description

| *addr*
| The address to set&period;


|===

== See Also


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






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