:relfileprefix: ../../../
[#CAD809F6272B6BFE2F49A0FBC89639922E01ACD6]

= Function params_encoded_base::contains

pass:v,q[Return true if a matching key exists]


== Synopsis

Declared in header `</boost/url/params_encoded_base.hpp#L267[boost/url/params_encoded_base.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
bool
contains(
    xref:boost/urls/pct_string_view.adoc[pct_string_view] key,
    xref:boost/urls/ignore_case_param.adoc[ignore_case_param] ic = = {}) const noexcept;
----

== Description

pass:v,q[This function examines the parameters] pass:v,q[in the container to find a match for]
pass:v,q[the specified key,]
pass:v,q[which may contain percent escapes.]
pass:v,q[The comparison is performed as if all]
pass:v,q[escaped characters were decoded first.]

=== Example
[,cpp]
----
assert( url_view( "?first=John&last=Doe" ).encoded_params().contains( "first" ) );
----

=== Complexity
pass:v,q[Linear in `this->buffer().size()`.]

=== Exception Safety
pass:v,q[Exceptions thrown on invalid input.]



== Return Value

* `bool` 


== Parameters

|===
| Name | Type 

| *key*
| `pct_string_view`

| *ic*
| `ignore_case_param`

|===