[Home]count

Synopsis

template<
      typename Sequence
    , typename T
    >
struct count
{
    typedef unspecified type;
};

Description

Returns the number of elements in a Sequence that are identical to T.

Definition

#include "boost/mpl/count.hpp"

Parameters

 Parameter  Requirement  Description  
SequenceA model of Forward SequenceA sequence to be examined.
TA typeThe type to be searched for.

Expression semantics

 Expression  Expression type  Precondition  Semantics  Postcondition 
typedef count<Sequence,T>::type n;A model of Integral ConstantEquivalent to typedef count_if< Sequence,is_same<_,T> >::type n;

Complexity

Linear. Exactly size<Sequence>::value comparisons for identity.

Example

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));

See also

Algorithms, count_if, find, find_if, contains


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Last edited December 12, 2002 2:05 am