NAME

std::array::swap - std::array::swap

Synopsis

void swap( array& other ) noexcept(/* see below */); (since C++11)
(until C++20)
constexpr void swap( array& other ) noexcept(/* see below */); (since C++20)

Exchanges the contents of the container with those of other. Does not cause
iterators and references to associate with the other container.

Parameters

other - container to exchange the contents with

Return value

(none)

Exceptions

noexcept specification:
noexcept(noexcept(swap(std::declval<T&>(), std::declval<T&>())))
(until C++17)
In the expression above, the identifier swap is looked up in the same
manner as the one used by the C++17 std::is_nothrow_swappable trait.
noexcept specification: (since C++17)
noexcept(std::is_nothrow_swappable_v<T>)

For zero-sized arrays,
noexcept specification:
noexcept

Complexity

Linear in size of the container.

Example

// Run this code

#include <array>
#include <iostream>

template<class Os, class V> Os& operator<<(Os& os, const V& v) {
os << "{";
for (auto i : v) os << ' ' << i;
return os << " } ";
}

int main()
{
std::array<int, 3> a1{1, 2, 3}, a2{4, 5, 6};

auto it1 = a1.begin();
auto it2 = a2.begin();
int& ref1 = a1[1];
int& ref2 = a2[1];

std::cout << a1 << a2 << *it1 << ' ' << *it2 << ' ' << ref1 << ' ' << ref2 << '\n';
a1.swap(a2);
std::cout << a1 << a2 << *it1 << ' ' << *it2 << ' ' << ref1 << ' ' << ref2 << '\n';

// Note that after swap iterators and references stay associated with their original
// array, e.g. `it1` still points to element a1[0], `ref1` still refers to a1[1].
}

Output:

{ 1 2 3 } { 4 5 6 } 1 4 2 5
{ 4 5 6 } { 1 2 3 } 4 1 5 2

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 2456 C++11 the noexcept specification is ill-formed made to work