[#boost-urls-params_base-count]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/params_base.adoc[params&lowbar;base]::count
:relfileprefix: ../../../
:mrdocs:


Return the number of matching keys

== Synopsis


Declared in `&lt;https://www.github.com/boostorg/url/blob/develop/include/boost/url/params_base.hpp#L299[boost&sol;url&sol;params&lowbar;base&period;hpp]&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
std::size&lowbar;t
count(
    core::string&lowbar;view key,
    xref:boost/urls/ignore_case_param.adoc[ignore&lowbar;case&lowbar;param] ic = &lcub;&rcub;) const noexcept;
----

== Description


This function examines the        parameters in the container to        find the number of matches for        the specified key&period;        The comparison is performed as if all        escaped characters were decoded first&period;


=== Example

[,cpp]
----
assert( url_view( "?first=John&last=Doe" ).params().count( "first" ) == 1 );
----

=== Complexity

Linear in `this&hyphen;&gt;buffer()&period;size()`&period;


=== Exception Safety

Throws nothing&period;



== Parameters


|===
| Name | Description

| *key*
| The key to match&period;        By default, a case&hyphen;sensitive        comparison is used&period;


| *ic*
| An optional parameter&period; If        the value xref:boost/urls/ignore_case.adoc[ignore&lowbar;case] is passed        here, the comparison is        case&hyphen;insensitive&period;


|===



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