std::iter_swap

 

C++

Language

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Freestanding and hosted implementations

Named requirements

Language support library

Concepts library(C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library(C++11)

Atomic operations library(C++11)

Thread support library(C++11)

Filesystem library(C++17)

Technical Specifications

 

Algorithm library

Constrained algorithms and algorithms on ranges (C++20)
Concepts and utilities: std::Sortable, std::projected, ...
Constrained algorithms: std::ranges::copy, std::ranges::sort, ...
Execution policies (C++17)
is_execution_policy	execution::seqexecution::parexecution::par_unseqexecution::unseq (C++20)	execution::sequenced_policyexecution::parallel_policyexecution::parallel_unsequenced_policyexecution::parallel_unsequenced (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	findfind_iffind_if_not (C++11) find_end find_first_of	search search_n lexicographical_compare lexicographical_compare_3way (C++20)
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)
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) destroy (C++17)	uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17) destroy_n (C++17)
Partitioning operations
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
Binary search operations
lower_bound	upper_bound	binary_search	equal_range
Set operations (on sorted ranges)
merge inplace_merge	set_difference set_intersection	set_symmetric_difference set_union	includes
Heap operations
is_heap (C++11) is_heap_until (C++11)	make_heap sort_heap	push_heap pop_heap
Minimum/maximum operations
max max_element	min min_element	minmax (C++11) minmax_element (C++11)	clamp (C++17) compare_3way (C++20)
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)	partial_sum inclusive_scan (C++17) exclusive_scan (C++17)	transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
C library
qsort	bsearch

 

Defined in header <algorithm>
template<class ForwardIt1, class ForwardIt2 > void iter_swap( ForwardIt1 a, ForwardIt2 b );		(until C++20)
template<class ForwardIt1, class ForwardIt2 > constexprvoid iter_swap( ForwardIt1 a, ForwardIt2 b );		(since C++20)

Swaps the values of the elements the given iterators are pointing to.

Parameters

a, b	-	iterators to the elements to swap
Type requirements
- ForwardIt1, ForwardIt2 must meet the requirements of LegacyForwardIterator.
- *a, *b must meet the requirements of Swappable.

Return value

(none)

Complexity

constant

Possible implementation

template<class ForwardIt1, class ForwardIt2>constexprvoid iter_swap(ForwardIt1 a, ForwardIt2 b)// constexpr since C++20{usingstd::swap; swap(*a, *b);}

Example

The following is an implementation of selection sort in C++

Run this code

#include <random>#include <vector>#include <iostream>#include <algorithm>#include <functional>   template<class ForwardIt>void selection_sort(ForwardIt begin, ForwardIt end){for(ForwardIt i = begin; i != end;++i) std::iter_swap(i, std::min_element(i, end));}   int main(){std::random_device rd;std::mt19937 gen(rd());std::uniform_int_distribution<> dist(-10, 10);std::vector<int> v; generate_n(back_inserter(v), 20, bind(dist, gen));   std::cout<<"Before sort: ";for(auto e : v)std::cout<< e <<" ";   selection_sort(v.begin(), v.end());   std::cout<<"\nAfter sort: ";for(auto e : v)std::cout<< e <<" ";std::cout<<'\n';}

Output:

Before sort: -7 6 2 4 -1 6 -9 -1 2 -5 10 -9 -5 -3 -5 -3 6 6 1 8 After sort: -9 -9 -7 -5 -5 -5 -3 -3 -1 -1 1 2 2 4 6 6 6 6 8 10

See also

swap	swaps the values of two objects (function template)
swap_ranges	swaps two ranges of elements (function template)