Difference between revisions of "cpp/utility/pair/swap2"
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| − | {{cpp/title | swap<small>(std::pair)</small>}} | + | {{cpp/title|swap<small>(std::pair)</small>}} |
{{cpp/utility/pair/navbar}} | {{cpp/utility/pair/navbar}} | ||
{{dcl begin}} | {{dcl begin}} | ||
| − | {{dcl header | utility}} | + | {{dcl header|utility}} |
| − | {{dcl rev multi | num=1 | + | {{dcl rev multi|num=1 |
| − | | since1=c++11 | dcl1= | + | |since1=c++11|dcl1= |
template< class T1, class T2 > | template< class T1, class T2 > | ||
| − | void swap( std::pair<T1,T2>& x, std::pair<T1,T2>& y ) noexcept(/* see below */); | + | void swap( std::pair<T1,T2>& x, std::pair<T1,T2>& y ) |
| − | | since2=c++20 | dcl2= | + | noexcept(/* see below */); |
| + | |since2=c++20|dcl2= | ||
template< class T1, class T2 > | template< class T1, class T2 > | ||
constexpr void swap( std::pair<T1,T2>& x, std::pair<T1,T2>& y ) | constexpr void swap( std::pair<T1,T2>& x, std::pair<T1,T2>& y ) | ||
noexcept(/* see below */); | noexcept(/* see below */); | ||
}} | }} | ||
| − | {{dcl | num=2 | + | {{dcl|num=2 |
| − | | since=c++23 | | + | |since=c++23| |
template< class T1, class T2 > | template< class T1, class T2 > | ||
constexpr void swap( const std::pair<T1,T2>& x, const std::pair<T1,T2>& y ) | constexpr void swap( const std::pair<T1,T2>& x, const std::pair<T1,T2>& y ) | ||
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===Parameters=== | ===Parameters=== | ||
{{par begin}} | {{par begin}} | ||
| − | {{par | x, y | pairs whose contents to swap}} | + | {{par|x, y|pairs whose contents to swap}} |
| − | {{par end}} | + | {{par end}} |
===Return value=== | ===Return value=== | ||
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===Exceptions=== | ===Exceptions=== | ||
{{noexcept|noexcept(x.swap(y))}} | {{noexcept|noexcept(x.swap(y))}} | ||
| + | |||
| + | ===Example=== | ||
| + | {{example| | ||
| + | |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} | ||
| + | }} | ||
===See also=== | ===See also=== | ||
Latest revision as of 15:55, 4 January 2023
| Defined in header <utility>
|
||
| (1) | ||
| (since C++11) (until C++20) |
||
| (since C++20) | ||
| (2) | (since C++23) | |
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) |
Contents |
[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}[edit] See also
| swaps the values of two objects (function template) | |
| (C++11) |
specializes the std::swap algorithm (function template) |
