Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Returns the key type associated with the element referenced by an associative iterator.
template< typename I > struct key_of { typedef unspecified type; };
Table 1.20. 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>));