[section:unique_copy unique_copy]

[heading Prototype]

``
template<class SinglePassRange, class OutputIterator>
OutputIterator unique_copy(const SinglePassRange& rng, OutputIterator out);

template<class SinglePassRange, class OutputIterator, class BinaryPredicate>
OutputIterator unique_copy(const SinglePassRange& rng, OutputIterator out, BinaryPredicate pred);
``

[heading Description]

`unique_copy` copies the first element of each sequence of duplicates encountered in `rng` to `out`.

Equality is determined by the predicate if one is supplied, or by `operator==()` for `SinglePassRange`'s value type.

[heading Definition]

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

[heading Requirements]

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

* `SinglePassRange` is a model of the __single_pass_range__ Concept.
* `SinglePassRange` is mutable.
* `SinglePassRange`'s value type is a model of the `EqualityComparableConcept`.
* `OutputIterator` is a model of the `OutputIteratorConcept`.

[*For the predicate versions of unique:]

* `SinglePassRange` is a model of the __single_pass_range__ Concept.
* `SinglePassRange` is mutable.
* `BinaryPredicate` is a model of the `BinaryPredicateConcept`.
* `SinglePassRange`'s value type is convertible to `BinaryPredicate`'s first argument type and to `BinaryPredicate`'s second argument type.
* `OutputIterator` is a model of the `OutputIteratorConcept`.

[heading Complexity]

Linear. `O(N)` where `N` is `distance(rng)`. Exactly `distance(rng)` comparisons are performed.

[endsect]