[#boost-urls-static_url-set_host]
= xref:boost/urls/static_url/set_host.adoc[boost::urls::static_url::set_host]
:relfileprefix: ../../../
:mrdocs:

Set the host

== Synopsis

Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/static_url.hpp#L376[boost/url/static_url.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/static_url.adoc[static_url]&
set_host(core::string_view s);
----

== Description

Depending on the contents of the passed string, this function sets the host:

* If the string is a valid IPv4 address, then the host is set to the address. The host type is `host_type::ipv4`.
* If the string is a valid IPv6 address enclosed in square brackets, then the host is set to that address. The host type is `host_type::ipv6`.
* If the string is a valid IPvFuture address enclosed in square brackets, then the host is set to that address. The host type is `host_type::ipvfuture`.
* Otherwise, the host name is set to the string, which may be empty. Reserved characters in the string are percent‐escaped in the result. The host type is `host_type::name`.

In all cases, when this function returns, the URL contains an authority.

== Example
[,cpp]
----
assert( url( "http://www.example.com" ).set_host( "127.0.0.1" ).buffer() == "http://127.0.0.1" );
----
== Postconditions
[,cpp]
----
this->has_authority() == true
----
== Complexity
Linear in `this‐>size() + s.size()`.

== Exception Safety
Strong guarantee. Calls to allocate may throw.

== BNF
[,cpp]
----
host        = IP-literal / IPv4address / reg-name

IP-literal  = "[" ( IPv6address / IPvFuture  ) "]"

reg-name    = *( unreserved / pct-encoded / "-" / ".")
----
== Specification
* https://en.wikipedia.org/wiki/IPv4[]
* https://datatracker.ietf.org/doc/html/rfc4291[]
* https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2[]

== Return Value

`*this`

== Parameters

[cols=2]
|===
| Name
| Description
| *s*
| The string to set.
|===

== See Also

xref:boost/urls/static_url/set_encoded_host.adoc[`set_encoded_host`], xref:boost/urls/static_url/set_encoded_host_address.adoc[`set_encoded_host_address`], xref:boost/urls/static_url/set_encoded_host_name.adoc[`set_encoded_host_name`], xref:boost/urls/static_url/set_host_address.adoc[`set_host_address`], xref:boost/urls/static_url/set_host_ipv4.adoc[`set_host_ipv4`], xref:boost/urls/static_url/set_host_ipv6.adoc[`set_host_ipv6`], xref:boost/urls/static_url/set_host_ipvfuture.adoc[`set_host_ipvfuture`], xref:boost/urls/static_url/set_host_name.adoc[`set_host_name`].


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