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std::iter_swap() algorithm

// (1)
template< class ForwardIt1, class ForwardIt2 >
constexpr void iter_swap( ForwardIt1 a, ForwardIt2 b );

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
LegacyForwardIterator
*a
*b
Swappable

Return value

(none)

Complexity

Constant.

Exceptions

(none)

Possible implementation

iter_swap(1)
template<class ForwardIt1, class ForwardIt2>
constexpr void iter_swap(ForwardIt1 a, ForwardIt2 b) // constexpr since C++20
{
using std::swap; // for ADL
swap(*a, *b);
}

Notes

This function template models the semantics of the swap operation given by Swappable. That is, overloads of swap found by ADL and the fall back of std::swap are considered.

Examples

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

Main.cpp
#include <algorithm>
#include <functional>
#include <iostream>
#include <random>
#include <vector>

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(-9, +9);
std::vector<int> v;
std::generate_n(back_inserter(v), 20, bind(dist, gen));

std::cout << "Before sort: " << std::showpos;
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: -9 -3 +2 -8 +0 -1 +8 -4 -5 +1 -4 -5 +4 -9 -8 -6 -6 +8 -4 -6
After sort : -9 -9 -8 -8 -6 -6 -6 -5 -5 -4 -4 -4 -3 -1 +0 +1 +2 +4 +8 +8
This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
Hover to see the original license.

std::iter_swap() algorithm

// (1)
template< class ForwardIt1, class ForwardIt2 >
constexpr void iter_swap( ForwardIt1 a, ForwardIt2 b );

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
LegacyForwardIterator
*a
*b
Swappable

Return value

(none)

Complexity

Constant.

Exceptions

(none)

Possible implementation

iter_swap(1)
template<class ForwardIt1, class ForwardIt2>
constexpr void iter_swap(ForwardIt1 a, ForwardIt2 b) // constexpr since C++20
{
using std::swap; // for ADL
swap(*a, *b);
}

Notes

This function template models the semantics of the swap operation given by Swappable. That is, overloads of swap found by ADL and the fall back of std::swap are considered.

Examples

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

Main.cpp
#include <algorithm>
#include <functional>
#include <iostream>
#include <random>
#include <vector>

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(-9, +9);
std::vector<int> v;
std::generate_n(back_inserter(v), 20, bind(dist, gen));

std::cout << "Before sort: " << std::showpos;
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: -9 -3 +2 -8 +0 -1 +8 -4 -5 +1 -4 -5 +4 -9 -8 -6 -6 +8 -4 -6
After sort : -9 -9 -8 -8 -6 -6 -6 -5 -5 -4 -4 -4 -3 -1 +0 +1 +2 +4 +8 +8
This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
Hover to see the original license.