std::swap(std::unordered_map) - cppreference.com (original) (raw)

| Defined in header <unordered_map> | | | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ------------------------------------- | | template< class Key, class T, class Hash, class KeyEqual, class Alloc > void swap( std::unordered_map<Key, T, Hash, KeyEqual, Alloc>& lhs, std::unordered_map<Key, T, Hash, KeyEqual, Alloc>& rhs ); | | (since C++11) (until C++17) | | template< class Key, class T, class Hash, class KeyEqual, class Alloc > void swap( std::unordered_map<Key, T, Hash, KeyEqual, Alloc>& lhs, std::unordered_map<Key, T, Hash, KeyEqual, Alloc>& rhs ) noexcept(/* see below */); | | (since C++17) (constexpr since C++26) |

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

[edit] Parameters

[edit] Complexity

Constant.

Exceptions

[edit] Example

#include #include #include   int main() { std::unordered_map<int, char> alice{{1, 'a'}, {2, 'b'}, {3, 'c'}}; std::unordered_map<int, char> bob{{7, 'Z'}, {8, 'Y'}, {9, 'X'}, {10, 'W'}};   auto print = <const int, char>& n) { std::cout << ' ' << n.first << ':' << n.second; };   // Print state before swap std::cout << "Alice:"; std::for_each(alice.begin(), alice.end(), print); std::cout << "\nBobby:"; 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 << "\nBobby:"; std::for_each(bob.begin(), bob.end(), print); std::cout << '\n'; }

Possible output:

Alice: 1:a 2:b 3:c Bobby: 7:Z 8:Y 9:X 10:W -- SWAP Alice: 7:Z 8:Y 9:X 10:W Bobby: 1:a 2:b 3:c

[edit] See also

| | swaps the contents (public member function) [edit] | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |