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std::array<T,N>::swap

From cppreference.com
< cpp‎ | container‎ | array
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.

Contents

[edit] Parameters

other - container to exchange the contents with

[edit] Return value

(none)

[edit] Exceptions

noexcept specification:  
noexcept(noexcept(swap(std::declval<T&>(), std::declval<T&>())))

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.

(until C++17)
noexcept specification:  
(since C++17)
For zero-sized arrays,
noexcept specification:  
noexcept
  

[edit] Complexity

Linear in size of the container.

[edit] Example

#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

[edit] 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

[edit] See also

specializes the std::swap algorithm
(function template) [edit]