[#BloombergLP-bdlc-FlatHashSet-contains-08] = xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlc.adoc[bdlc]::xref:BloombergLP/bdlc/FlatHashSet.adoc[FlatHashSet]::contains :relfileprefix: ../../../ :mrdocs: Return `true` if this set contains an element whose key is equivalent to the specified `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; ---- [.small]#Created with https://www.mrdocs.com[MrDocs]#