std::deque<T,Allocator>::swap

 

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std::deque

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deque::deque deque::~deque deque::operator=	deque::assign deque::assign_range (哋它亢++23) deque::get_allocator
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Non-member functions
operator==operator!=operator<operator>operator<=operator>=operator<=> (until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(哋它亢++20)	swap(std::deque) erase(std::deque)erase_if(std::deque) (哋它亢++20)(哋它亢++20)
Deduction guides(哋它亢++17)

 

void swap( deque& other );		(until 哋它亢++17)
void swap( deque& other ) noexcept(/* see below */);		(since 哋它亢++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 end() iterator is invalidated.

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

(since 哋它亢++11)

Parameters

other

-

container to exchange the contents with

Return value

(none)

Exceptions

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

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 associated 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)