:relfileprefix: ../../../
[#FA6D558C8D31B60CA4166BD1C5E72A6645C904D8]

= Function params_base::contains

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


== Synopsis

Declared in header `</boost/url/params_base.hpp#L262[boost/url/params_base.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
bool
contains(
    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[The comparison is performed as if all]
pass:v,q[escaped characters were decoded first.]

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

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

=== Exception Safety
pass:v,q[Throws nothing.]



== Return Value

* `bool` 


== Parameters

|===
| Name | Type 

| *key*
| `string_view`

| *ic*
| `ignore_case_param`

|===