std::rotate_copy() algorithm
- since C++20
- since C++17
- until C++17
// (1)
template< class ForwardIt, class OutputIt >
constexpr OutputIt rotate_copy( ForwardIt first, ForwardIt n_first,
ForwardIt last, OutputIt d_first );
// (2)
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2 >
ForwardIt2 rotate_copy( ExecutionPolicy&& policy,
ForwardIt1 first, ForwardIt1 n_first,
ForwardIt1 last, ForwardIt2 d_first );
// (1)
template< class ForwardIt, class OutputIt >
OutputIt rotate_copy( ForwardIt first, ForwardIt n_first,
ForwardIt last, OutputIt d_first );
// (2)
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2 >
ForwardIt2 rotate_copy( ExecutionPolicy&& policy,
ForwardIt1 first, ForwardIt1 n_first,
ForwardIt1 last, ForwardIt2 d_first );
// (1)
template< class ForwardIt, class OutputIt >
OutputIt rotate_copy( ForwardIt first, ForwardIt n_first,
ForwardIt last, OutputIt d_first );
-
(1) Copies the elements from the range [
first
;last
), to another range beginning atd_first
in such a way, that the element*(n_first)
becomes the first element of the new range and*(n_first - 1)
becomes the last element. -
(2) Same as (1), but executed according to
policy
.Overload ResolutionThese overloads participate in overload resolution only if
std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>
(until C++20)std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>
(since C++20) istrue
.
The behavior is undefined
if either [first
; n_first
) or [n_first
; last
) is not a valid range, or the source and destination ranges overlap.Parameters
first last | The range of elements to copy. |
n_first | An iterator to an element in [ |
d_first | The beginning of the destination range. |
policy | The execution policy to use. See execution policy for details. |
Type requirements
ForwardIt1 ForwardIt2 ForwardIt3 | LegacyForwardIterator |
OutputIt | LegacyOutputIterator |
Return value
Output iterator to the element past the last element copied.
Complexity
Given N
as std::distance(first, last)
:
Linear in N.
Exceptions
The overloads with a template parameter named ExecutionPolicy
report errors as follows:
- If execution of a function invoked as part of the algorithm throws an exception and
ExecutionPolicy
is one of the 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.
Possible implementation
rotate_copy (1)
template<class ForwardIt, class OutputIt>
constexpr // since C++20
OutputIt rotate_copy(ForwardIt first, ForwardIt n_first,
ForwardIt last, OutputIt d_first)
{
d_first = std::copy(n_first, last, d_first);
return std::copy(first, n_first, d_first);
}
Examples
The following copy-prints a vector, replacing all values over 5
with 99
on the fly.
#include <algorithm>
#include <iostream>
#include <iterator>
#include <vector>
int main()
{
std::vector<int> src {1, 2, 3, 4, 5};
std::vector<int> dest(src.size());
auto pivot = std::find(src.begin(), src.end(), 3);
std::rotate_copy(src.begin(), pivot, src.end(), dest.begin());
for (int i : dest)
std::cout << i << ' ';
std::cout << '\n';
// copy the rotation result directly to the std::cout
pivot = std::find(dest.begin(), dest.end(), 1);
std::rotate_copy(dest.begin(), pivot, dest.end(),
std::ostream_iterator<int>(std::cout, " "));
std::cout << '\n';
}
3 4 5 1 2
1 2 3 4 5
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