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

Identifies a known URL scheme

== Synopsis

Declared in `&lt;https://www.github.com/boostorg/url/blob/develop/include/boost/url/scheme.hpp#Lundefined[boost&sol;url&sol;scheme&period;hpp]&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
enum class scheme : unsigned short;
----

== Specification

* https://datatracker.ietf.org/doc/html/rfc3986#section-3.1[3&period;1&period; Scheme (rfc3986)]

== Members

[cols="1,4"]
|===
| Name| Description
| `none` 
| Indicates that no scheme is present
| `unknown` 
| Indicates the scheme is not a well&hyphen;known scheme
| `ftp` 
| File Transfer Protocol (FTP)
| `file` 
| File URI Scheme
| `http` 
| The Hypertext Transfer Protocol URI Scheme
| `https` 
| The Secure Hypertext Transfer Protocol URI Scheme
| `ws` 
| The WebSocket URI Scheme
| `wss` 
| The Secure WebSocket URI Scheme
|===

== Non-Member Functions

[cols="1,4"]
|===
| Name
| Description
| xref:boost/urls/default_port.adoc[`default&lowbar;port`]
| Return the default port for a known scheme
| xref:boost/urls/string_to_scheme.adoc[`string&lowbar;to&lowbar;scheme`]
| Return the known scheme for a non&hyphen;normalized string, if known
| xref:boost/urls/to_string.adoc[`to&lowbar;string`]
| Return the normalized string for a known scheme
|===


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