|  | Home | Libraries | People | FAQ | More | 
Returns the key type associated with the element referenced by an associative iterator.
template< typename I > struct key_of { typedef unspecified type; };
Table 1.19. Parameters
| Parameter | Requirement | Description | 
|---|---|---|
| 
                     | Model of Associative Iterator | Operation's argument | 
result_of::key_of<I>::type
Return type: Any type
          Semantics: Returns the key type associated
          with the element referenced by an associative iterator I.
        
#include <boost/fusion/iterator/key_of.hpp> #include <boost/fusion/include/key_of.hpp>
typedefmap<pair<float,int> > vec; typedefresult_of::begin<vec>::type first; BOOST_MPL_ASSERT((boost::is_same<result_of::key_of<first>::type, float>));