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


Return true a scheme is present

== Synopsis


Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/url_view_base.hpp#L352[boost/url/url_view_base.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
bool
has_scheme() const noexcept;
----

== Description


This function returns true if this        contains a scheme.


=== Example

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

=== Complexity

Constant.


=== Exception Safety

Throws nothing.


=== BNF

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

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

scheme          = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
----

=== Specification

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

Return true a scheme is present

This function returns true if this        contains a scheme.


=== Example

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

=== Complexity

Constant.


=== Exception Safety

Throws nothing.


=== BNF

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

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

scheme          = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
----

=== Specification

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



== See Also


xref:boost/urls/url_view_base/scheme.adoc[scheme],            xref:boost/urls/url_view_base/scheme_id.adoc[scheme_id].



xref:boost/urls/url_view_base/scheme.adoc[scheme],            xref:boost/urls/url_view_base/scheme_id.adoc[scheme_id].






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