std::swap(std::pair)
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C++
Feature test macros (C++20)
Concepts library (C++20)
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Execution control library (C++26)
Utilities library
Type support (basic types, RTTI)
Library feature-test macros (C++20)
(C++11)
(C++20)
(C++26)
(C++20)
Coroutine support (C++20)
Contract support (C++26)
(C++20)(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
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(C++20)
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(C++20)(C++20)(C++20)
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General utilities
Relational operators (deprecated in C++20)
(C++20)(C++20)(C++20)
(C++20)(C++20)(C++20)
(C++20)
Swap and type operations
Common vocabulary types
std::pair
(C++11)
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
swap(std::pair)
(C++11)
(C++11)
(C++11)
(C++11)
(C++23)
(C++23)
(C++11)
Deduction guides (C++17)
Defined in header
<utility>
(1)
template< class T1, class T2 >
(since C++11) void swap( std::pair <T1,T2>& x, std::pair <T1,T2>& y )
(until C++20)
template< class T1, class T2 >
(since C++20)
constexpr void swap( std::pair <T1,T2>& x, std::pair <T1,T2>& y )
template< class T1, class T2 >
(2)
(since C++23)
constexpr void swap( const std::pair <T1,T2>& x, const std::pair <T1,T2>& y )
Swaps the contents of x and y. Equivalent to x.swap(y).
1) This overload participates in overload resolution only if std::is_swappable_v <first_type> && std::is_swappable_v <second_type> is true.
2) This overload participates in overload resolution only if std::is_swappable_v <const first_type> && std::is_swappable_v <const second_type> is true.
(since C++17)[edit] Parameters
x, y
-
pairs whose contents to swap
[edit] Return value
(none)
[edit] Exceptions
noexcept specification:
noexcept(noexcept(x.swap(y)))
[edit] Example
Run this code
#include <iostream> #include <utility> int main() { auto p1 = std::make_pair (10, 3.14); auto p2 = std::pair (12, 1.23); // CTAD, since C++17 auto print_p1_p2 = [&](auto msg) { std::cout << msg << "p1 = {" << std::get<0>(p1) << ", " << std::get<1>(p1) << "}, " << "p2 = {" << std::get<0>(p2) << ", " << std::get<1>(p2) << "}\n"; }; print_p1_p2("Before p1.swap(p2): "); p1.swap(p2); print_p1_p2("After p1.swap(p2): "); std::swap (p1, p2); print_p1_p2("After swap(p1, p2): "); }
Output:
Before p1.swap(p2): p1 = {10, 3.14}, p2 = {12, 1.23}
After p1.swap(p2): p1 = {12, 1.23}, p2 = {10, 3.14}
After swap(p1, p2): p1 = {10, 3.14}, p2 = {12, 1.23}