:relfileprefix: ../../../
[#E377F1A20682E6856A7DABA1C17C8DE2CE226C43]

= Function url_view_base::scheme

pass:v,q[Return the scheme]


== Synopsis

Declared in header `</boost/url/url_view_base.hpp#L375[boost/url/url_view_base.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
string_view
scheme() const noexcept;
----

== Description

pass:v,q[This function returns the scheme if it] pass:v,q[exists, without a trailing colon (':').]
pass:v,q[Otherwise it returns an empty string.]
pass:v,q[Note that schemes are case-insensitive,]
pass:v,q[and the canonical form is lowercased.]

=== Example
[,cpp]
----
assert( url_view( "http://www.example.com" ).scheme() == "http" );
----

=== Exception Safety
pass:v,q[Throws nothing.]

=== BNF
[,cpp]
----
scheme          = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )

URI             = scheme ":" hier-part [ "?" query ] [ "#" fragment ]

absolute-URI    = scheme ":" hier-part [ "?" query ]
----

=== Specification

* link:https://datatracker.ietf.org/doc/html/rfc3986#section-3.1[3.1. Scheme (rfc3986)]



== Return Value

* `string_view`