std::iter_swap() algorithm
- since C++20
- until C++20
// (1)
template< class ForwardIt1, class ForwardIt2 >
constexpr void iter_swap( ForwardIt1 a, ForwardIt2 b );
// (1)
template< class ForwardIt1, class ForwardIt2 >
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
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