std::swap(std::tuple)

 

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tuple::swap

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std::swap

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Defined in header <tuple>
	(1)
template< class... Types > void swap( std::tuple<Types...>& lhs,            std::tuple<Types...>& rhs ) noexcept(/* see below */);			(since C++11) (until C++20)
template< class... Types > constexpr void swap( std::tuple<Types...>& lhs,                      std::tuple<Types...>& rhs ) noexcept(/* see below */);			(since C++20)
template< class... Types > constexpr void swap( const std::tuple<Types...>& lhs,                      const std::tuple<Types...>& rhs ) noexcept(/* see below */);		(2)	(since C++23)

Swaps the contents of lhs and rhs. Equivalent to lhs.swap(rhs).

1) This overload participates in overload resolution only if std::is_swappable_v<Ti> is true for all i from 0 to sizeof...(Types). 2) This overload participates in overload resolution only if std::is_swappable_v<const Ti> is true for all i from 0 to sizeof...(Types).

(since C++17)

Parameters

lhs, rhs

-

tuples whose contents to swap

Return value

(none)

Exceptions

noexcept specification:  

noexcept(noexcept(lhs.swap(rhs)))

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}

See also

swap (C++11)	swaps the contents of two tuples (public member function)
std::swap(std::pair) (C++11)	specializes the std::swap algorithm (function template)