[ceph.git] / ceph / src / boost / libs / range / doc / reference / algorithm / count_if.qbk

[/
    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_if count_if]

[heading Prototype]

``
template<class SinglePassRange, class UnaryPredicate>
typename range_difference<const SinglePassRange>::type
count_if(const SinglePassRange& rng, UnaryPredicate pred);
``

[heading Description]

`count_if` returns the number of elements `x` in `rng` where `pred(x)` is `true`.

[heading Definition]

Defined in the header file `boost/range/algorithm/count_if.hpp`

[heading Requirements]

* `SinglePassRange` is a model of the __single_pass_range__ Concept.
* `UnaryPredicate` is a model of the `UnaryPredicateConcept`.
* `SinglePassRange`'s value type is a model of the `EqualityComparableConcept`.
* The value type of `SinglePassRange` is convertible to the argument type of `UnaryPredicate`.

[heading Complexity]

Linear. Exactly `distance(rng)` invocations of `pred`.

[endsect]
Commit	Line	Data
7c673cae FG	1	[/
	2	Copyright 2010 Neil Groves
	3	Distributed under the Boost Software License, Version 1.0.
	4	(See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
	5	/]
	6	[section:count_if count_if]
	7
	8	[heading Prototype]
	9
	10	``
	11	template<class SinglePassRange, class UnaryPredicate>
	12	typename range_difference<const SinglePassRange>::type
	13	count_if(const SinglePassRange& rng, UnaryPredicate pred);
	14	``
	15
	16	[heading Description]
	17
	18	`count_if` returns the number of elements `x` in `rng` where `pred(x)` is `true`.
	19
	20	[heading Definition]
	21
	22	Defined in the header file `boost/range/algorithm/count_if.hpp`
	23
	24	[heading Requirements]
	25
	26	* `SinglePassRange` is a model of the __single_pass_range__ Concept.
	27	* `UnaryPredicate` is a model of the `UnaryPredicateConcept`.
	28	* `SinglePassRange`'s value type is a model of the `EqualityComparableConcept`.
	29	* The value type of `SinglePassRange` is convertible to the argument type of `UnaryPredicate`.
	30
	31	[heading Complexity]
	32
	33	Linear. Exactly `distance(rng)` invocations of `pred`.
	34
	35	[endsect]
	36
	37