[#boost-urls-static_url-set_host]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/static_url.adoc[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#L374[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

* link:https://en.wikipedia.org/wiki/IPv4[IPv4 (Wikipedia)]
        
* link:https://datatracker.ietf.org/doc/html/rfc4291[IP Version 6 Addressing Architecture (rfc4291)]
        
* link:https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2[            3.2.2. Host (rfc3986)]



== Parameters


|===
| Name | Description

| *s*
| The string to set.


|===

== See Also


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






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