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std::tuple::swap(3)	      C++ Standard Libary	   std::tuple::swap(3)

NAME
       std::tuple::swap	- std::tuple::swap

Synopsis
	  Defined in header <tuple>
	  void	 swap(	 tuple&	  other	  )   noexcept(/*   see	  below	  */);
       (since C++11)
										 (un-
       til C++20)
	  constexpr void swap( tuple& other ) noexcept(/* see below  */);  (1)
       (since C++20)
	  constexpr   void   swap(   const  tuple&  other  )  noexcept(/*  see
       (2) (since C++23)
	  below	*/) const;

	  Calls	swap (which might be std::swap,	or might be found via ADL) for
       each element in
	  *this	and its	corresponding element in other.

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

Parameters
	  other	- tuple	of values to swap

Return value
	  (none)

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&>()))	    &&
       (until C++17)
	  ...

	  )

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

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}

	 Defect	reports

	  The following	behavior-changing defect reports were applied retroac-
       tively 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

See also
	  std::swap(std::tuple)	specializes the	std::swap algorithm
	  (C++11)		(function template)
	  swap			swaps the contents
	  (C++11)		(public	member function	of std::pair<T1,T2>)

http://cppreference.com		  2022.07.31		   std::tuple::swap(3)

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