[#boost-urls-ipv6_address]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::ipv6_address
:relfileprefix: ../../
:mrdocs:


An IP version 6 style address.

== Synopsis


Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/ipv6_address.hpp#L64[boost/url/ipv6_address.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class ipv6_address;
----

== Types

[cols=2]
|===
| Name | Description 

| xref:boost/urls/ipv6_address/bytes_type.adoc[`bytes_type`] 
| The type used to represent an address as an array of bytes.

|===
== Member Functions

[cols=2]
|===
| Name | Description 

| xref:boost/urls/ipv6_address/2constructor.adoc[`ipv6_address`]         [.small]#[constructor]#
| Construct from a string.

Construct from an IPv4 address.

Construct from an array of bytes.

Constructor.


| xref:boost/urls/ipv6_address/is_loopback.adoc[`is_loopback`] 
| Return true if the address is a loopback address

| xref:boost/urls/ipv6_address/is_unspecified.adoc[`is_unspecified`] 
| Return true if the address is unspecified

| xref:boost/urls/ipv6_address/is_v4_mapped.adoc[`is_v4_mapped`] 
| Return true if the address is a mapped IPv4 address

| xref:boost/urls/ipv6_address/operator_assign.adoc[`operator=`] 
| Copy Assignment

| xref:boost/urls/ipv6_address/to_buffer.adoc[`to_buffer`] 
| Write a dotted decimal string representing the address to a buffer

| xref:boost/urls/ipv6_address/to_bytes.adoc[`to_bytes`] 
| Return the address as bytes, in network byte order

| xref:boost/urls/ipv6_address/to_string.adoc[`to_string`] 
| Return the address as a string.

|===
== Static Member Functions

[cols=2]
|===
| Name | Description 

| xref:boost/urls/ipv6_address/loopback.adoc[`loopback`] 
| Return an address object that represents the loopback address

|===
== Static Data Members

[cols=2]
|===
| Name | Description 

| xref:boost/urls/ipv6_address/max_str_len.adoc[`max_str_len`] 
| The number of characters in the longest possible IPv6 string.

|===
== Friends

[cols=2]
|===
| Name | Description 

| xref:boost/urls/ipv6_address/08friend-01.adoc[`operator!=`] 
| Return true if two addresses are not equal

| xref:boost/urls/ipv6_address/08friend-09.adoc[`operator<<`] 
| Format the address to an output stream

| xref:boost/urls/ipv6_address/08friend-0d.adoc[`operator==`] 
| Return true if two addresses are equal

|===



== Description


Objects of this type are used to construct,    parse, and manipulate IP version 6 addresses.


=== BNF

[,cpp]
----
IPv6address =                            6( h16 ":" ) ls32
            /                       "::" 5( h16 ":" ) ls32
            / [               h16 ] "::" 4( h16 ":" ) ls32
            / [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
            / [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
            / [ *3( h16 ":" ) h16 ] "::"    h16 ":"   ls32
            / [ *4( h16 ":" ) h16 ] "::"              ls32
            / [ *5( h16 ":" ) h16 ] "::"              h16
            / [ *6( h16 ":" ) h16 ] "::"

ls32        = ( h16 ":" h16 ) / IPv4address
            ; least-significant 32 bits of address

h16         = 1*4HEXDIG
            ; 16 bits of address represented in hexadecimal
----

=== Specification

* 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)]



== See Also


xref:boost/urls/ipv4_address.adoc[ipv4_address],        xref:boost/urls/parse_ipv6_address.adoc[parse_ipv6_address].






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