std::swap(std::deque)

Defined in header `<deque>`
template< class T, class Alloc > void swap( std::deque<T,Alloc>& lhs, std::deque<T,Alloc>& rhs );		(until C++17)
template< class T, class Alloc > void swap( std::deque<T,Alloc>& lhs, std::deque<T,Alloc>& rhs ) noexcept(/* see below */);		(since C++17)

Specializes the std::swap algorithm for std::deque. Swaps the contents of lhs and rhs. Calls lhs.swap(rhs).

Parameters

lhs, rhs

-

containers whose contents to swap

Return value

(none)

Complexity

Constant.

Exceptions

noexcept specification:

noexcept(noexcept(lhs.swap(rhs)))

(since C++17)

Notes

Although the overloads of std::swap for container adaptors are introduced in C++11, container adaptors can already be swapped by std::swap in C++98. Such calls to std::swap usually have linear time complexity, but better complexity may be provided.

Example

Run this code

#include <algorithm>
#include <iostream>
#include <deque>
 
int main()
{
    std::deque<int> alice{1, 2, 3};
    std::deque<int> bob{7, 8, 9, 10};
 
    auto print = [](const int& n) { std::cout << ' ' << n; };
 
    // Print state before swap
    std::cout << "alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\n" "bob  :";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';
 
    std::cout << "-- SWAP\n";
    std::swap(alice, bob);
 
    // Print state after swap
    std::cout << "alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\n" "bob  :";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';
}

Output:

alice: 1 2 3
bob  : 7 8 9 10
-- SWAP
alice: 7 8 9 10
bob  : 1 2 3

Compiler support
Freestanding and hosted
Language
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Technical specifications
Symbols index
External libraries

Sequence
array (C++11)
vector
deque
forward_list (C++11)
list
Associative
set
multiset
map
multimap
Unordered associative
unordered_set (C++11)
unordered_multiset (C++11)
unordered_map (C++11)
unordered_multimap (C++11)
Adaptors
stack
queue
priority_queue
Views
span (C++20)

Member functions
deque::deque
deque::~deque
deque::operator=
deque::assign
deque::get_allocator
Element access
deque::at
deque::operator[]
deque::front
deque::back
Iterators
deque::begindeque::cbegin (C++11)
deque::enddeque::cend (C++11)
deque::rbegindeque::crbegin (C++11)
deque::renddeque::crend (C++11)
Capacity
deque::empty
deque::size
deque::max_size
deque::shrink_to_fit
Modifiers
deque::clear
deque::insert
deque::emplace
deque::erase
deque::push_front
deque::emplace_front
deque::pop_front
deque::push_back
deque::emplace_back
deque::pop_back
deque::resize
deque::swap
Non-member functions
std::swap
eraseerase_if (C++20)(C++20)
operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
Deduction guides(C++17)