:relfileprefix: ../../../
[#boost-urls-url_view_base-empty]

= xref:boost.adoc[pass:[boost]]::xref:boost/urls.adoc[pass:[urls]]::xref:boost/urls/url_view_base.adoc[pass:[url_view_base]]::empty


Return true if the url is empty


== Synopsis

Declared in header `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/url_view_base.hpp#L201[boost/url/url_view_base.hpp,window=blank_]>`

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

== Description


The empty string matches the
_relative-ref_
grammar.

=== Example
[,cpp]
----
assert( url_view( "" ).empty() );
----

=== Complexity

Constant.

=== Exception Safety

Throws nothing.

=== BNF
[,cpp]
----
relative-ref  = relative-part [ "?" query ] [ "#" fragment ]

relative-part = "//" authority path-abempty
              / path-absolute
              / path-noscheme
              / path-empty
----

=== Specification

* link:https://datatracker.ietf.org/doc/html/rfc3986#section-4.2[4.2.  Relative Reference (rfc3986)]