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std::tuple::swap

From cppreference.com
< cpp‎ | utility‎ | tuple
Defined in header <tuple>
void swap( tuple& other ) noexcept(/* see below */);
(since C++11)

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

Contents

[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++17 std::is_nothrow_swappable trait.

(until C++17)
noexcept specification:  
noexcept(

    std::is_nothrow_swappable<T0>::value &&
    std::is_nothrow_swappable<T1>::value &&
    std::is_nothrow_swappable<T2>::value &&
    ...

)
(since C++17)

[edit] Example

#include <iostream>
#include <tuple>
#include <string>
 
int main()
{
    std::tuple<int, std::string, float> p1, p2;
    p1 = std::make_tuple(10, "test", 3.14);
    p2.swap(p1);
    std::cout << "("  << std::get<0>(p2)
              << ", " << std::get<1>(p2)
              << ", " << std::get<2>(p2) << ")\n";
}

Output:

(10, test, 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