libs/range/doc/reference/algorithm/count.qbk
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Copyright 2010 Neil Groves
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/]
[section:count count]
[heading Prototype]
``
template<class SinglePassRange, class Value>
typename range_difference<SinglePassRange>::type
count(SinglePassRange& rng, const Value& val);
template<class SinglePassRange, class Value>
typename range_difference<const SinglePassRange>::type
count(const SinglePassRange& rng, const Value& val);
``
[heading Description]
`count` returns the number of elements `x` in `rng` where `x == val` is `true`.
[heading Definition]
Defined in the header file `boost/range/algorithm/count.hpp`
[heading Requirements]
* `SinglePassRange` is a model of the __single_pass_range__ Concept.
* `Value` is a model of the `EqualityComparableConcept`.
* `SinglePassRange`'s value type is a model of the `EqualityComparableConcept`.
* An object of `SinglePassRange`'s value type can be compared for equality with an object of type `Value`.
[heading Complexity]
Linear. Exactly `distance(rng)` comparisons.
[endsect]
