std::unordered_map::swap

From cppreference.com

void swap( unordered_map& other );
(since C++11)

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.

The Hash and KeyEqual objects must be Swappable, and they are exchanged using unqualified calls to non-member swap.

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 C++11)

Contents

[edit] Parameters

other - container to exchange the contents with

[edit] Return value

(none)

[edit] Exceptions

Any exception thrown by the swap Hash or KeyEqual objects.

(until C++17)
noexcept specification:  
noexcept(std::allocator_traits<Allocator>::is_always_equal::value

&& noexcept(std::swap(std::declval<Hash&>(),std::declval<Hash&>()))

&& noexcept(std::swap(std::declval<KeyEqual&>(),std::declval<KeyEqual&>())))
(since C++17)

[edit] Complexity

Constant.

[edit] See also

specializes the std::swap algorithm
(function template)