[section:adjacent_find adjacent_find]

[heading Prototype]

``
template<class ForwardRange>
typename range_iterator<ForwardRange>::type
adjacent_find(ForwardRange& rng);

template<class ForwardRange>
typename range_iterator<const ForwardRange>::type
adjacent_find(const ForwardRange& rng);

template<class ForwardRange, class BinaryPredicate>
typename range_iterator<ForwardRange>::type
adjacent_find(ForwardRange& rng, BinaryPred pred);

template<class ForwardRange, class BinaryPredicate>
typename range_iterator<const ForwardRange>::type
adjacent_find(const ForwardRange& rng, BinaryPred pred);

template<range_return_value_re, class ForwardRange>
typename range_return<ForwardRange, re>::type
adjacent_find(ForwardRange& rng);

template<range_return_value_re, class ForwardRange>
typename range_return<const ForwardRange, re>::type
adjacent_find(const ForwardRange& rng);

template<
    range_return_value re,
    class ForwardRange,
    class BinaryPredicate
    >
typename range_return<ForwardRange, re>::type
adjacent_find(ForwardRange& rng, BinaryPredicate pred);

template<
    range_return_value re,
    class ForwardRange,
    class BinaryPredicate
    >
typename range_return<const ForwardRange, re>::type
adjacent_find(const ForwardRange& rng, BinaryPredicate pred);
``

[heading Description]

[*Non-predicate versions:]

`adjacent_find` finds the first adjacent elements `[x,y]` in `rng` where `x == y`

[*Predicate versions:]

`adjacent_find` finds the first adjacent elements `[x,y]` in `rng` where `pred(x,y)` is `true`.

[heading Definition]

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

[heading Requirements]

[*For the non-predicate versions of adjacent_find:]

* `ForwardRange` is a model of the __forward_range__ Concept.
* `ForwardRange`'s value type is a model of the `EqualityComparableConcept`.

[*For the predicate versions of adjacent_find:]

* `ForwardRange` is a model of the __forward_range__ Concept.
* `BinaryPredicate` is a model of the `BinaryPredicateConcept`.
* `ForwardRange`'s value type is convertible to `BinaryPredicate`'s first argument type and to `BinaryPredicate`'s second argument type.

[heading Complexity]

Linear. If `empty(rng)` then no comparisons are performed; otherwise, at most `distance(rng) - 1` comparisons.

[endsect]