std::reverse_copy
From cppreference.com
| Defined in header <algorithm>
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| template< class BidirIt, class OutputIt > OutputIt reverse_copy( BidirIt first, BidirIt last, OutputIt d_first ); |
(1) | |
| template< class ExecutionPolicy, class BidirIt, class ForwardIt > ForwardIt reverse_copy( ExecutionPolicy&& policy, BidirIt first, BidirIt last, ForwardIt d_first ); |
(2) | (since C++17) |
1) Copies the elements from the range
[first, last) to another range beginning at d_first in such a way that the elements in the new range are in reverse order. Behaves as if by executing the assignment *(d_first + (last - first) - 1 - i) = *(first + i) once for each non-negative
i < (last - first) If the source and destination ranges (that is,
[first, last) and [d_first, d_first+(last-first)) respectively) overlap, the behavior is undefined.2) Same as (1), but executed according to
policy. This overload does not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is trueContents |
[edit] Parameters
| first, last | - | the range of elements to copy |
| d_first | - | the beginning of the destination range |
| Type requirements | ||
-BidirIt must meet the requirements of BidirectionalIterator.
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-OutputIt must meet the requirements of OutputIterator.
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-ForwardIt must meet the requirements of ForwardIterator.
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[edit] Return value
Output iterator to the element past the last element copied.
[edit] Exceptions
The overload with a template parameter named ExecutionPolicy reports errors as follows:
- If execution of a function invoked as part of the algorithm throws an exception and
ExecutionPolicyis one of the three standard policies, std::terminate is called. For any otherExecutionPolicy, the behavior is implementation-defined. - If the algorithm fails to allocate memory, std::bad_alloc is thrown.
[edit] Possible implementation
template<class BidirIt, class OutputIt> OutputIt reverse_copy(BidirIt first, BidirIt last, OutputIt d_first) { while (first != last) { *(d_first++) = *(--last); } return d_first; } |
[edit] Example
Run this code
#include <vector> #include <iostream> #include <algorithm> int main() { std::vector<int> v({1,2,3}); for (const auto& value : v) { std::cout << value << " "; } std::cout << '\n'; std::vector<int> destination(3); std::reverse_copy(std::begin(v), std::end(v), std::begin(destination)); for (const auto& value : destination) { std::cout << value << " "; } std::cout << '\n'; }
Output:
1 2 3 3 2 1
[edit] Complexity
Linear in the distance between first and last
[edit] See also
| reverses the order of elements in a range (function template) |