std::swap_ranges

 

C++

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Technical Specifications

 

Algorithm library

Constrained algorithms and algorithms on ranges(C++20)
Constrained algorithms, e.g. std::ranges::copy, std::ranges::sort, ...
Execution policies (C++17)
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
all_ofany_ofnone_of (C++11)(C++11)(C++11) for_each for_each_n (C++17)	countcount_if mismatch equal adjacent_find	search search_n lexicographical_compare lexicographical_compare_three_way (C++20)	findfind_iffind_if_not (C++11) find_end find_first_of
Modifying sequence operations
copycopy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) shift_leftshift_right (C++20)(C++20) transform	fill fill_n generate generate_n swap iter_swap swap_ranges sample (C++17)	removeremove_if replacereplace_if reverse rotate unique random_shuffle (until C++17)	remove_copyremove_copy_if replace_copyreplace_copy_if reverse_copy rotate_copy unique_copy shuffle (C++11)
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is_partitioned (C++11) partition_point (C++11)	partition partition_copy (C++11)	stable_partition
Sorting operations
is_sorted (C++11) is_sorted_until (C++11)	sort stable_sort	partial_sort partial_sort_copy	nth_element
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lower_bound	upper_bound	binary_search	equal_range
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merge inplace_merge	set_difference set_intersection	set_symmetric_difference set_union	includes
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is_heap (C++11) is_heap_until (C++11)	make_heap sort_heap	push_heap pop_heap
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max max_element	min min_element	minmax (C++11) minmax_element (C++11)	clamp (C++17)
Permutations
is_permutation (C++11)	next_permutation	prev_permutation
Numeric operations
iota (C++11) inner_product adjacent_difference	accumulate reduce (C++17) transform_reduce (C++17)	transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)	partial_sum inclusive_scan (C++17) exclusive_scan (C++17)
Operations on uninitialized storage
uninitialized_copy uninitialized_move (C++17) uninitialized_fill	uninitialized_copy_n (C++11) uninitialized_move_n (C++17) uninitialized_fill_n	uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17)	destroy (C++17) destroy_n (C++17) destroy_at (C++17) construct_at (C++20)
C library
qsort	bsearch

 

Defined in header <algorithm>
	(1)
template<class ForwardIt1, class ForwardIt2 > ForwardIt2 swap_ranges( ForwardIt1 first1, ForwardIt1 last1,                         ForwardIt2 first2 );			(until C++20)
template<class ForwardIt1, class ForwardIt2 > constexpr ForwardIt2 swap_ranges( ForwardIt1 first1, ForwardIt1 last1,                                   ForwardIt2 first2 );			(since C++20)
template<class ExecutionPolicy, class ForwardIt1, class ForwardIt2 > ForwardIt2 swap_ranges( ExecutionPolicy&& policy,                         ForwardIt1 first1, ForwardIt1 last1, ForwardIt2 first2 );		(2)	(since C++17)

1) Exchanges elements between range [first1, last1) and another range starting at first2.

Precondition: the two ranges [first1, last1) and [first2, last2) do not overlap, where last2 =std::next(first2, std::distance(first1, last1)).

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

Parameters

first1, last1	-	the first range of elements to swap
first2	-	beginning of the second range of elements to swap
policy	-	the execution policy to use. See execution policy for details.
Type requirements
- ForwardIt1, ForwardIt2 must meet the requirements of LegacyForwardIterator.
- The types of dereferenced ForwardIt1 and ForwardIt2 must meet the requirements of Swappable

Return value

Iterator to the element past the last element exchanged in the range beginning with first2.

Complexity

linear in the distance between first1 and last1.

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

template<class ForwardIt1, class ForwardIt2>constexpr ForwardIt2 swap_ranges(ForwardIt1 first1, ForwardIt1 last1, ForwardIt2 first2){while(first1 != last1){std::iter_swap(first1++, first2++);}return first2;}

Example

Demonstrates swapping of subranges from different containers.

Run this code

#include <list>#include <vector>#include <iostream>#include <algorithm>   auto print =[](auto comment, autoconst& seq){std::cout<< comment;for(constauto& e : seq){std::cout<< e <<' ';}std::cout<<'\n';};   int main(){std::vector<char> v ={'a', 'b', 'c', 'd', 'e'};std::list<char> l ={'1', '2', '3', '4', '5'};   print("Before swap_ranges:\n""v: ", v); print("l: ", l);   std::swap_ranges(v.begin(), v.begin()+3, l.begin());   print("After swap_ranges:\n""v: ", v); print("l: ", l);}

Output:

Before swap_ranges: v: a b c d e l: 1 2 3 4 5 After swap_ranges: v: 1 2 3 d e l: a b c 4 5

See also

iter_swap	swaps the elements pointed to by two iterators (function template)
swap	swaps the values of two objects (function template)
ranges::swap_ranges (C++20)	swaps two ranges of elements (niebloid)