std::pair<T1,T2>::swap - cppreference.com (original) (raw)
| (1) | ||
|---|---|---|
| void swap( pair& other ) noexcept(/* see below */); | (since C++11) (until C++20) | |
| constexpr void swap( pair& other ) noexcept(/* see below */); | (since C++20) | |
| constexpr void swap( const pair& other ) const noexcept(/* see below */); | (2) | (since C++23) |
Swaps first with other.first and second with other.second, as if by using std::swap; swap(first, other.first); swap(second, other.second);.
| If either selected swap function call is ill-formed or does not swap the value of the member, the behavior is undefined. | (until C++23) |
|---|---|
| If either selected swap function call does not swap the value of the member, the behavior is undefined. | (since C++23) |
[edit] Parameters
| other | - | pair of values to swap |
|---|
[edit] Return value
(none)
[edit] Exceptions
[edit] Example
#include #include #include int main() { std::pair<int, std::string> p1(10, "test"), p2; p2.swap(p1); std::cout << "(" << p2.first << ", " << p2.second << ")\n"; #if __cpp_lib_ranges_zip >= 202110L // Using the C++23 const qualified swap overload // (swap is no longer propagating pair constness) int i1 = 10, i2{}; std::string s1("test"), s2; const std::pair<int&, std::string&> r1(i1, s1), r2(i2, s2); r2.swap(r1); std::cout << "(" << i2 << ", " << s2 << ")\n"; #endif }
Possible output:
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2456 | C++11 | the noexcept specification is ill-formed | made to work |
[edit] See also
| | swaps the values of two objects (function template) [edit] | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | swaps the contents of two tuples (public member function of std::tuple<Types...>) [edit] |