std::rotate_copy

 

C++

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Constrained algorithms and algorithms on ranges (C++20)
Constrained algorithms, e.g. ranges::copy, ranges::sort, ...
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is_execution_policy (C++17)   execution::seqexecution::parexecution::par_unseqexecution::unseq (C++17)    (C++17)(C++17)(C++20)	execution::sequenced_policyexecution::parallel_policyexecution::parallel_unsequenced_policyexecution::parallel_unsequenced (C++17)(C++17)(C++17)(C++20)
Non-modifying sequence operations Batch operations for_each for_each_n (C++17) Search operations all_ofany_ofnone_of (C++11)                (C++11)(C++11) countcount_if mismatch equal findfind_iffind_if_not (C++11) find_end find_first_of adjacent_find search search_n Modifying sequence operations Copy operations copycopy_if (C++11) copy_backward copy_n (C++11) move (C++11) move_backward (C++11) Swap operations swap iter_swap swap_ranges Transformation operations replacereplace_if transform replace_copyreplace_copy_if Generation operations fill fill_n generate generate_n Removing operations removeremove_if unique remove_copyremove_copy_if unique_copy Order-changing operations reverse reverse_copy rotate rotate_copy random_shuffleshuffle (until C++17)(C++11) shift_leftshift_right (C++20)(C++20) Sampling operations sample (C++17)	Sorting and related operations Partitioning operations partition partition_copy (C++11)   stable_partition is_partitioned (C++11) partition_point (C++11) Sorting operations sort stable_sort partial_sort partial_sort_copy is_sorted (C++11) is_sorted_until (C++11) nth_element Binary search operations (on partitioned ranges) lower_bound upper_bound equal_range binary_search Set operations (on sorted ranges) includes set_union set_intersection set_difference set_symmetric_difference Merge operations (on sorted ranges) merge inplace_merge Heap operations push_heap pop_heap make_heap sort_heap is_heap (C++11) is_heap_until (C++11) Minimum/maximum operations max min minmax (C++11) clamp (C++17) max_element min_element minmax_element (C++11) Lexicographical comparison operations lexicographical_compare lexicographical_compare_three_way (C++20) Permutation operations next_permutation prev_permutation is_permutation (C++11) C library qsort bsearch
Numeric operations
iota (C++11) inner_product adjacent_difference    accumulate reduce (C++17) transform_reduce (C++17)	partial_sum inclusive_scan (C++17)    exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
Operations on uninitialized memory
uninitialized_copy uninitialized_move (C++17)    uninitialized_fill uninitialized_copy_n (C++11) uninitialized_move_n (C++17) uninitialized_fill_n	destroy (C++17) destroy_n (C++17) destroy_at (C++17) construct_at (C++20)       uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17)

 

Defined in header <algorithm>
template< class ForwardIt, class OutputIt > OutputIt rotate_copy( ForwardIt first, ForwardIt n_first,                       ForwardIt last, OutputIt d_first );	(1)	(constexpr since C++20)
template< class ExecutionPolicy,           class ForwardIt1, class ForwardIt2 > ForwardIt2 rotate_copy( ExecutionPolicy&& policy,                         ForwardIt1 first, ForwardIt1 n_first,                         ForwardIt1 last, ForwardIt2 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 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.

This overload participates in overload resolution only if

std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true.	(until C++20)
std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>> is true.	(since C++20)

If any of the following conditions is satisfied, the behavior is undefined:

• [first, n_first) or [n_first, last) is not a valid range.
• The source and destination ranges overlap.

Parameters

first, last	-	the range of elements to copy
n_first	-	an iterator to an element in [first, last) that should appear at the beginning of the new range
d_first	-	beginning of the destination range
policy	-	the execution policy to use. See execution policy for details.
Type requirements
- ForwardIt, ForwardIt1, ForwardIt2 must meet the requirements of LegacyForwardIterator.
- OutputIt must meet the requirements of LegacyOutputIterator.

Return value

Output iterator to the element past the last element copied.

Complexity

Exactly std::distance(first, last) assignments.

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 ExecutionPolicy is one of the standard policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
• If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Possible implementation

See also the implementations in libstdc++, libc++, and MSVC STL.

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); }

Example

Run this code

#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';
}

Output:

3 4 5 1 2
1 2 3 4 5

See also

rotate	rotates the order of elements in a range (function template)
ranges::rotate_copy (C++20)	copies and rotate a range of elements (niebloid)