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std::deque::swap(3)	      C++ Standard Libary	   std::deque::swap(3)

NAME
       std::deque::swap	- std::deque::swap

Synopsis
	  void swap( deque& other );				(until C++17)
	  void swap( deque& other ) noexcept(/*	see below */);	(since C++17)

	  Exchanges  the  contents  of the container with those	of other. Does
       not invoke any
	  move,	copy, or swap operations on individual elements.

	  All iterators	and references remain valid. The past-the-end iterator
       is invalidated.

	  If	      std::allocator_traits<allocator_type>::propagate_on_con-
       tainer_swap::value
	  is true, then	the allocators are exchanged using an unqualified call
       to	(since
	  non-member swap. Otherwise, they are not swapped (and	if get_alloca-
       tor() !=	  C++11)
	  other.get_allocator(), the behavior is undefined).

Parameters
	  other	- container to exchange	the contents with

Return value
	  (none)

Exceptions
	  (none)
       (until C++17)
	  noexcept						specification:
       (since C++17)
	  noexcept(std::allocator_traits<Allocator>::is_always_equal::value)

Complexity
	  Constant.

Example
       // Run this code

	#include <iostream>
	#include <deque>

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

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

	    auto it1 = std::next(a1.begin());
	    auto it2 = std::next(a2.begin());

	    int& ref1 =	a1.front();
	    int& ref2 =	a2.front();

	    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 the	iterators and references stay  associ-
       ated with their
	    //	original elements, e.g.	it1 that pointed to an element in 'a1'
       with value 2
	    // still points to the same	element, though	this element was moved
       into 'a2'.
	}

Output:
	{ 1 2 3	} { 4 5	} 2 5 1	4
	{ 4 5 }	{ 1 2 3	} 2 5 1	4

See also
	  std::swap(std::deque)	specializes the	std::swap algorithm
				(function template)

http://cppreference.com		  2022.07.31		   std::deque::swap(3)

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