:relfileprefix: ../../../ [#boost-urls-url_view_base-host_ipv4_address] == xref:boost.adoc[pass:[boost]]::xref:boost/urls.adoc[pass:[urls]]::xref:boost/urls/url_view_base.adoc[pass:[url_view_base]]::host_ipv4_address Return the host IPv4 address === Synopsis Declared in header `` [source,cpp,subs="verbatim,macros,-callouts"] ---- xref:boost/urls/ipv4_address.adoc[ipv4_address] host_ipv4_address() const noexcept; ---- === Description If the host type is xref:boost/urls/host_type/ipv4.adoc[host_type::ipv4] , this function returns the address as a value of type xref:boost/urls/ipv4_address.adoc[ipv4_address] . Otherwise, if the host type is not an IPv4 address, it returns a default-constructed value which is equal to the unspecified address "0.0.0.0". [,cpp] ---- assert( url_view( "http://127.0.0.1/index.htm?user=win95" ).host_ipv4_address() == ipv4_address( "127.0.0.1" ) ); ---- === Constant. === Throws nothing. [,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 ---- * link:https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2[3.2.2. Host (rfc3986)]