:relfileprefix: ../../../
[#boost-urls-url_base-params-0c]

= xref:boost.adoc[pass:[boost]]::xref:boost/urls.adoc[pass:[urls]]::xref:boost/urls/url_base.adoc[pass:[url_base]]::params


Return the query as a container of parameters


== Synopsis

Declared in header `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/url_base.hpp#L2138[boost/url/url_base.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
xref:boost/urls/params_ref.adoc[params_ref]
params(xref:boost/urls/encoding_opts.adoc[encoding_opts] opt) noexcept;
----

== Description


This function returns a bidirectional
view of key&sol;value pairs over the query.
The returned view references the same
underlying character buffer; ownership
is not transferred.
Any percent-escapes in strings returned
when iterating the view are decoded first.
The container is modifiable; changes
to the container are reflected in the
underlying URL.

=== Example
[,cpp]
----
encoding_opts opt;
opt.space_as_plus = true;
params_ref pv = url( "/sql?id=42&name=jane+doe&page+size=20" ).params(opt);
----

=== Complexity

Constant.

=== Exception Safety

Throws nothing.

=== BNF
[,cpp]
----
query           = *( pchar / "/" / "?" )

query-param     = key [ "=" value ]
query-params    = [ query-param ] *( "&" query-param )
----

=== Specification

* link:https://datatracker.ietf.org/doc/html/rfc3986#section-3.4[3.4.  Query (rfc3986)]

* link:https://en.wikipedia.org/wiki/Query_string[Query string (Wikipedia)]





== Parameters

|===
| Name | Description 

| *opt*
| 
The options for decoding. If
this parameter is omitted, the `space_as_plus`
is used.

|===




== See Also


xref:boost/urls/url_base/encoded_params-06.adoc[encoded_params]
,
xref:boost/urls/url_base/remove_query.adoc[remove_query]
,
xref:boost/urls/url_base/set_encoded_query.adoc[set_encoded_query]
,
xref:boost/urls/url_base/set_query.adoc[set_query]
.