[#bsl-unordered_set-09-count-01]
= xref:bsl.adoc[bsl]::xref:bsl/unordered_set-09.adoc[unordered_set<Attribute, AttributeHash>]::count
:relfileprefix: ../../
:mrdocs:

Return the number of `value_type` objects within this unordered set that are equivalent to the specified `key`. The behavior is undefined unless `key` is equivalent to at most one element in this unordered set. Note that since an unordered set maintains unique keys, the returned value will be either 0 or 1.

== Synopsis

Declared in `<bslstl_unorderedset.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class LOOKUP_KEY>
xref:bsl/unordered_set-09/size_type.adoc[size_type]
count(LOOKUP_KEY const& key) const
requires BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value;
----

== Description

Note: implemented inline due to Sun CC compilation error.


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