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Returns the element associated with a Key from the sequence.
template <typename Key, typename Sequence> typenameresult_of::at_key<Sequence, Key>::type at_key(Sequence& seq); template <typename Key, typename Sequence> typenameresult_of::at_key<Sequence const, Key>::type at_key(Sequence const& seq);
| Parameter | Requirement | Description | 
|---|---|---|
| 
                       | Model of Associative Sequence | The sequence we wish to investigate. | 
| 
                       | Any type | The queried key. | 
at_key<Key>(seq);
            Return type: Returns a reference to
            the element associated with Key from the sequence seq
            if seq is mutable and
            e =
            o, where e
            is the element associated with Key, is a valid expression. Else, returns
            a type convertible to the element associated with Key.
          
            Precondition: has_key<Key>(seq) == true (where seq
            is not Unbounded
            Sequence)
          
Semantics: Returns the element associated with Key.
#include <boost/fusion/sequence/intrinsic/at_key.hpp> #include <boost/fusion/include/at_key.hpp>
set<int, char, bool> s(1, 'x', true);
assert(at_key<char>(s) == 'x');