std::swap(std::unordered_map)
From cppreference.com
< cpp | container | unordered map
| Defined in header <unordered_map>
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| template< class Key, class T, class Hash, class KeyEqual, class Alloc > void swap( std::unordered_map<Key, T, Hash, KeyEqual, Alloc>& lhs, |
(since C++11) (until C++17) |
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template< class Key, class T, class Hash, class KeyEqual, class Alloc > void swap( std::unordered_map<Key, T, Hash, KeyEqual, Alloc>& lhs, |
(since C++17) (constexpr since C++26) |
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Specializes the std::swap algorithm for std::unordered_map. Swaps the contents of lhs and rhs. Calls lhs.swap(rhs).
Contents |
[edit] Parameters
| lhs, rhs | - | containers whose contents to swap |
[edit] Complexity
Constant.
Exceptions
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noexcept specification:
noexcept(noexcept(lhs.swap(rhs))) |
(since C++17) |
[edit] Example
Run this code
#include <algorithm> #include <iostream> #include <unordered_map> 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 = [](std::pair<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) |
