[section:copy_backward copy_backward]

[heading Prototype]

``
template<class BidirectionalRange, class BidirectionalOutputIterator>
    BidirectionalOutputIterator
        copy_backward(const BidirectionalRange& source_rng,
                      BidirectionalOutputIterator out_it);
``

[heading Description]

`copy_backward` copies all elements from `source_rng` to the range `[out_it - distance(source_rng), out_it)`.

The values are copied in reverse order. The return value is `out_it - distance(source_rng)`.

Note well that unlike all other standard algorithms `out_it` denotes the *end* of the output sequence.

[heading Definition]

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

[heading Requirements]

* `BidirectionalRange` is a model of __bidirectional_range__ Concept.
* `OutputIterator` is a model of the `OutputIteratorConcept`.
* The `value_type` of __bidirectional_range__ Concept is convertible to a type in `OutputIterator`'s set of value types.

[heading Precondition:]

* `out_it` is not an iterator within the `source_rng`.
* `[out_it, out_it + distance(source_rng))` is a valid range.

[heading Complexity]

Linear. Exactly `distance(source_rng)` assignments are performed.

[endsect]