:relfileprefix: ../../
[#5624456C086AC9FCEBCB6A8C414C4A252BEC1105]

= Function string_to_scheme

pass:v,q[Return the known scheme for a non-normalized string, if known]


== Synopsis

Declared in header `</boost/url/scheme.hpp#L141[boost/url/scheme.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
xref:boost/urls/scheme.adoc[scheme]
string_to_scheme(string_view s) noexcept;
----

== Description

pass:v,q[If the string does not identify a known] pass:v,q[scheme, the value] xref:boost/urls/scheme/unknown.adoc[scheme::unknown]
pass:v,q[is]
pass:v,q[returned.]

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

=== Specification

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



== Return Value

* `scheme` 


== Parameters

|===
| Name | Type 

| *s*
| `string_view`

|===