std::experimental::ranges::copy, std::experimental::ranges::copy_if
| Defined in header <experimental/ranges/algorithm>
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| template < ranges::InputIterator I, ranges::Sentinel<I> S, ranges::WeaklyIncrementable O > requires ranges::IndirectlyCopyable<I, O>() |
(1) | (ranges TS) |
| template < ranges::InputRange Rng, ranges::WeaklyIncrementable O > requires ranges::IndirectlyCopyable<ranges::iterator_t<Rng>, O>() |
(2) | (ranges TS) |
| template < ranges::InputIterator I, ranges::Sentinel<I> S, ranges::WeaklyIncrementable O, class Proj = ranges::identity, |
(3) | (ranges TS) |
| template < ranges::InputRange Rng, ranges::WeaklyIncrementable O, class Proj = ranges::identity, |
(4) | (ranges TS) |
Copies elements in the source range ([first,last) or rng) into the destination range beginning at result, starting from the first element in the source range and proceeding to the last one.
[first, last). For each non-negative integer n < (last - first), performs *(result + n) = *(first + n). The behavior is undefined if result is within the range [first, last). In this case, ranges::copy_backward may be used instead.rng as the source range, as if by ranges::copy(ranges::begin(rng), ranges::end(rng), result); except that result may not be copied.pred returns true when applied to the element's value as projected by the projection proj. The order of the elements that are copied is preserved. The behavior is undefined if the source and the destination ranges overlap.rng as the source range, as if by ranges::copy_if(ranges::begin(rng), ranges::end(rng), result, pred, proj); except that result, pred and proj may not be copied.Contents |
[edit] Parameters
| first, last | - | the range of elements to copy |
| rng | - | the range of elements to copy |
| result | - | the beginning of the destination range |
| pred | - | predicate to apply to the projected elements |
| proj | - | projection to apply to the elements |
[edit] Return value
A tagged_pair object containing the following two members:
- The first member, with the tag
tag::in, is the past-the-end iterator of the source range (that is, an iterator of typeIthat compares equal to the sentinellast). - The second member, with the tag
tag::out, is the past-the-end iterator of the result range.
[edit] Complexity
[edit] Possible implementations
| First version |
|---|
template <ranges::InputIterator I, ranges::Sentinel<I> S, ranges::WeaklyIncrementable O> requires ranges::IndirectlyCopyable<I, O>() ranges::tagged_pair<ranges::tag::in(I), ranges::tag::out(O)> copy(I first, S last, O result) { for (; first != last; ++first, (void)++result) *result = *first; return {first, result}; } |
| Second version |
template <ranges::InputRange Rng, ranges::WeaklyIncrementable O> requires ranges::IndirectlyCopyable<ranges::iterator_t<Rng>, O>() ranges::tagged_pair<ranges::tag::in(ranges::safe_iterator_t<Rng>), ranges::tag::out(O)> copy(Rng&& rng, O result) { return ranges::copy(ranges::begin(rng), ranges::end(rng), result); } |
| Third version |
template <ranges::InputIterator I, ranges::Sentinel<I> S, ranges::WeaklyIncrementable O, class Proj = ranges::identity, ranges::IndirectPredicate<ranges::projected<I, Proj>> Pred> requires ranges::IndirectlyCopyable<I, O>() ranges::tagged_pair<ranges::tag::in(I), ranges::tag::out(O)> copy_if(I first, S last, O result, Pred pred, Proj proj = Proj{}) { for (; first != last; ++first) { if (ranges::invoke(pred, ranges::invoke(proj, *first))){ *result = *first; ++result; } } return {first, result}; } |
| Fourth version |
template <ranges::InputRange Rng, ranges::WeaklyIncrementable O, class Proj = ranges::identity, ranges::IndirectPredicate<ranges::projected<ranges::iterator_t<Rng>, Proj>> Pred> requires ranges::IndirectlyCopyable<ranges::iterator_t<Rng>, O>() ranges::tagged_pair<ranges::tag::in(ranges::safe_iterator_t<Rng>), ranges::tag::out(O)> copy_if(Rng&& rng, O result, Pred pred, Proj proj = Proj{}) { return ranges::copy_if(ranges::begin(rng), ranges::end(rng), result, pred, proj); } |
[edit] Example
The following code uses copy to both copy the contents of one vector to another and to display the resulting vector:
#include <experimental/ranges/algorithm> #include <iostream> #include <vector> #include <experimental/ranges/iterator> #include <numeric> int main() { // see http://en.cppreference.com/w/cpp/language/namespace_alias namespace ranges = std::experimental::ranges; std::vector<int> from_vector(10); std::iota(from_vector.begin(), from_vector.end(), 0); std::vector<int> to_vector; ranges::copy_if(from_vector.begin(), from_vector.end(), ranges::back_inserter(to_vector), [](const auto i) { return i % 3; }); // or, alternatively, // std::vector<int> to_vector(from_vector.size()); // std::copy(from_vector, to_vector.begin()); std::cout << "to_vector contains: "; ranges::copy(to_vector, ranges::ostream_iterator<int>(std::cout, " ")); std::cout << '\n'; }
Output:
to_vector contains: 1 2 4 5 7 8
[edit] See also
| (C++11) |
copies a range of elements to a new location (function template) |
| copies a range of elements in backwards order (function template) | |
| creates a copy of a range that is reversed (function template) | |
| copies a number of elements to a new location (function template) | |
| assigns a range of elements a certain value (function template) | |
| copies a range of elements omitting those that satisfy specific criteria (function template) |