:relfileprefix: ../../../ [#boost-urls-url_base-set_host] == xref:boost.adoc[pass:[boost]]::xref:boost/urls.adoc[pass:[urls]]::xref:boost/urls/url_base.adoc[pass:[url_base]]::set_host Set the host === Synopsis Declared in header `` [source,cpp,subs="verbatim,macros,-callouts"] ---- xref:boost/urls/url_base.adoc[url_base]& 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 xref:boost/urls/host_type/ipv4.adoc[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 xref:boost/urls/host_type/ipv6.adoc[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 xref:boost/urls/host_type/ipvfuture.adoc[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 xref:boost/urls/host_type/name.adoc[host_type::name] . In all cases, when this function returns, the URL contains an authority. [,cpp] ---- assert( url( "http://www.example.com" ).set_host( "127.0.0.1" ).buffer() == "http://127.0.0.1" ); ---- [,cpp] ---- this->has_authority() == true ---- === Linear in `this->size() + s.size()`. === Strong guarantee. Calls to allocate may throw. [,cpp] ---- host = IP-literal / IPv4address / reg-name IP-literal = "[" ( IPv6address / IPvFuture ) "]" reg-name = *( unreserved / pct-encoded / "-" / ".") ---- * 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] .