std::tuple<Types...>::swap

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std::tuple

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tuple::tuple
tuple::operator=
tuple::swap
Non-member functions
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tie
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operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
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get(std::tuple)
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Defined in header`<tuple>`
void swap( tuple& other)noexcept(/* see below */);	(1)	(since C++11) (constexpr since C++20)
constexprvoid swap(const tuple& other)noexcept(/* see below */)const;	(2)	(since C++23)

Callsswap (which might bestd::swap, or might be found viaADL) for each element in*this and its corresponding element inother.

If any selected`swap` function call is ill-formed, or does not swap the corresponding elements of both tuples, the behavior is undefined.	(until C++23)
If any selected`swap` function call does not swap the corresponding elements of both tuples, the behavior is undefined. 1) The program is ill-formed if(std::is_swappable_v<Types>&& ...) is nottrue. 2) The program is ill-formed if(std::is_swappable_v<const Types>&& ...) is nottrue.	(since C++23)

[edit]Parameters

other

tuple of values to swap

[edit]Return value

(none)

[edit]Exceptions

`noexcept` specification: noexcept( noexcept(swap(std::declval<T0&>>(),std::declval<T0&>()))&& noexcept(swap(std::declval<T1&>>(),std::declval<T1&>()))&& noexcept(swap(std::declval<T2&>>(),std::declval<T2&>()))&& ... ) In the expression above, the identifier`swap` is looked up in the same manner as the one used by the C++17std::is_nothrow_swappable trait.	(until C++17)
1) `noexcept` specification: noexcept((std::is_nothrow_swappable_v<Types>&& ...)) 2) `noexcept` specification: noexcept((std::is_nothrow_swappable_v<const Types>&& ...))	(since C++17)

[edit]Example

Run this code

#include <iostream>#include <string>#include <tuple> int main(){std::tuple<int,std::string,float> p1{42,"ABCD",2.71}, p2;    p2=std::make_tuple(10,"1234",3.14); auto print_p1_p2=[&](auto rem){std::cout<< rem<<"p1 = {"<< std::get<0>(p1)<<", "<< std::get<1>(p1)<<", "<< std::get<2>(p1)<<"}, "<<"p2 = {"<< std::get<0>(p2)<<", "<< std::get<1>(p2)<<", "<< std::get<2>(p2)<<"}\n";};     print_p1_p2("Before p1.swap(p2): ");    p1.swap(p2);    print_p1_p2("After  p1.swap(p2): ");    swap(p1, p2);    print_p1_p2("After swap(p1, p2): ");}

Output:

Before p1.swap(p2): p1 = {42, ABCD, 2.71}, p2 = {10, 1234, 3.14}After  p1.swap(p2): p1 = {10, 1234, 3.14}, p2 = {42, ABCD, 2.71}After swap(p1, p2): p1 = {42, ABCD, 2.71}, p2 = {10, 1234, 3.14}

[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

std::swap(std::tuple) (C++11)	specializes thestd::swap algorithm (function template)[edit]
swap (C++11)	swaps the contents (public member function of`std::pair<T1,T2>`)[edit]