[#BloombergLP-bdlc-FlatHashSet-contains-08]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlc.adoc[bdlc]::xref:BloombergLP/bdlc/FlatHashSet.adoc[FlatHashSet]::contains
:relfileprefix: ../../../
:mrdocs:

Return whether this set contains an element equivalent to `key`.

== Synopsis

Declared in `<bdlc_flathashset.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class LOOKUP_KEY>
bool
contains(LOOKUP_KEY const& key) const
requires BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        &&  BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value;
----

== Return Value

`true` if an element with `key` exists, and `false` otherwise

== Parameters

[cols="1,4"]
|===
| Name| Description
| *key*
| key to look up
|===


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