source:
downloads/boost_1_33_1/libs/mpl/doc/src/refmanual/count.rst
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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.
Header
#include <boost/mpl/count.hpp>
Parameters
| Parameter | Requirement | Description |
|---|---|---|
| Sequence | |Forward Sequence| | A sequence to be examined. |
| T | Any type | A type to search for. |
Expression semantics
For any |Forward Sequence| s and arbitrary type t:
typedef count<s,t>::type n;
| Return type: | |
|---|---|
| Semantics: | Equivalent to typedef count_if< s,is_same<_,T> >::type n; |
Complexity
Linear. Exactly size<s>::value comparisons for identity.
Example
typedef vector<int,char,long,short,char,short,double,long> types; typedef count<types, short>::type n; BOOST_MPL_ASSERT_RELATION( n::value, ==, 2 );
See also
|Querying Algorithms|, |count_if|, |find|, |find_if|, |contains|, |lower_bound|
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