template< typename Sequence , typename T > struct count { typedef unspecified type; };
Returns the number of elements in a Sequence
that are identical to T
.
#include "boost/mpl/count.hpp"
Parameter | Requirement | Description |
---|---|---|
Sequence | A model of Forward Sequence | A sequence to be examined. |
T | A type | The type to be searched for. |
Expression | Expression type | Precondition | Semantics | Postcondition |
---|---|---|---|---|
typedef count<Sequence,T>::type n; | A model of Integral Constant | Equivalent to typedef count_if< Sequence,is_same<_,T> >::type n; |
Linear. Exactly size<Sequence>::value
comparisons for identity.
typedef list<int,char,long,short,char,short,double,long> types; typedef find<types, short>::type iter; BOOST_STATIC_ASSERT((is_same<iter::type,short>::type::value)); BOOST_STATIC_ASSERT((distance< begin<types>::type,iter >::type::value == 3));
Algorithms, count_if
, find
, find_if
, contains