[section:transform transform]

[heading Prototype]

``
template<
    class SinglePassRange1,
    class OutputIterator,
    class UnaryOperation
>
OutputIterator transform(const SinglePassRange1& rng,
                         OutputIterator out,
                         UnaryOperation fun);

template<
    class SinglePassRange1,
    class SinglePassRange2,
    class OutputIterator,
    class BinaryOperation
>
OutputIterator transform(const SinglePassRange1& rng1,
                         const SinglePassRange2& rng2,
                         OutputIterator out,
                         BinaryOperation fun);
``

[heading Description]

[*UnaryOperation version:]

`transform` assigns the value `y` to each element `[out, out + distance(rng)), y = fun(x)` where `x` is the corresponding value to `y` in `rng1`. The return value is `out + distance(rng)`.

[*BinaryOperation version:]

`transform` assigns the value `z` to each element `[out, out + min(distance(rng1), distance(rng2))), z = fun(x,y)` where `x` is the corresponding value in `rng1` and `y` is the corresponding value in `rng2`. This version of `transform` stops upon reaching either the end of `rng1`, or the end of `rng2`. Hence there isn't a requirement for `distance(rng1) == distance(rng2)` since there is a safe guaranteed behaviour, unlike with the iterator counterpart in the standard library.

The return value is `out + min(distance(rng1), distance(rng2))`.

[heading Definition]

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

[heading Requirements]

[*For the unary versions of transform:]

* `SinglePassRange1` is a model of the __single_pass_range__ Concept.
* `OutputIterator` is a model of the `OutputIteratorConcept`.
* `UnaryOperation` is a model of the `UnaryFunctionConcept`.
* `SinglePassRange1`'s value type must be convertible to `UnaryFunction`'s argument type.
* `UnaryFunction`'s result type must be convertible to a type in `OutputIterator`'s set of value types.

[*For the binary versions of transform:]

* `SinglePassRange1` is a model of the __single_pass_range__ Concept.
* `SinglePassRange2` is a model of the __single_pass_range__ Concept.
* `OutputIterator` is a model of the `OutputIteratorConcept`.
* `BinaryOperation` is a model of the `BinaryFunctionConcept`.
* `SinglePassRange1`'s value type must be convertible to `BinaryFunction`'s first argument type.
* `SinglePassRange2`'s value type must be convertible to `BinaryFunction`'s second argument type.
* `BinaryOperation`'s result type must be convertible to a type in `OutputIterator`'s set of value types.

[heading Precondition:]

[*For the unary version of transform:]

* `out` is not an iterator within the range `[begin(rng1) + 1, end(rng1))`.
* `[out, out + distance(rng1))` is a valid range.

[*For the binary version of transform:]

* `out` is not an iterator within the range `[begin(rng1) + 1, end(rng1))`.
* `out` is not an iterator within the range `[begin(rng2) + 1, end(rng2))`.
* `[out, out + min(distance(rng1), distance(rng2)))` is a valid range.


[heading Complexity]

Linear. The operation is applied exactly `distance(rng1)` for the unary version and `min(distance(rng1), distance(rng2))` for the binary version.

[endsect]