# Boost.Range

## Range Adaptors

#### `transformed`

>     rng | boost::adaptors::transformed( fun )

>     boost::make_transformed_range( rng, fun )

- Precondition: The value-type of the range is convertible to the argument type of fun.
- Postcondition: For all elements `x` in the returned range, `x` is the result of `fun(y)` where `y` is the corresponding element in the original range.
- Throws: Whatever the copy-constructor of `fun` might throw.
- Range Category: SinglePassRange

### Example

            #include <boost/range/adaptor/transformed.hpp>
            #include <boost/range/algorithm/copy.hpp>
            #include <boost/range/assign.hpp>
            #include <algorithm>
            #include <iostream>
            #include <vector>

            struct double_int
            {
                typedef int result_type;
                int operator()(int x) const { return x * 2; }
            };

            int main(int argc, const char* argv[])
            {
                using namespace boost::adaptors;
                using namespace boost::assign;

                std::vector<int> input;
                input += 1,2,3,4,5,6,7,8,9,10;

                boost::copy(
                    input | transformed(double_int()),
                    std::ostream_iterator<int>(std::cout, ","));

                return 0;
            }

This produces the output:
`2,4,6,8,10,12,14,16,18,20`

(C) Copyright Neil Groves 2009 (C) Copyright Thorsten Ottosen 2003-2004