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std:: swap (std::tuple)

From cppreference.net
C++
Utilities library
std::tuple
定义于头文件 <tuple>
(1)
template < class ... Types >

void swap ( std:: tuple < Types... > & lhs,

std:: tuple < Types... > & rhs ) noexcept ( /* see below */ ) ;
(C++11 起)
(C++20 前)
template < class ... Types >

constexpr void swap ( std:: tuple < Types... > & lhs,

std:: tuple < Types... > & rhs ) noexcept ( /* see below */ ) ;
(C++20 起)
template < class ... Types >

constexpr void swap ( const std:: tuple < Types... > & lhs,

const std:: tuple < Types... > & rhs ) noexcept ( /* see below */ ) ;
(2) (C++23 起)

交换 lhs 与 rhs 的内容。等价于 lhs. swap ( rhs ) 。

1) 仅当对所有从 0 到 sizeof... ( Types ) 的 i， std:: is_swappable_v < Ti > 为 true 时，此重载才参与重载决议。
2) 仅当对所有从 0 到 sizeof... ( Types ) 的 i， std:: is_swappable_v < const Ti > 为 true 时，此重载才参与重载决议。
(since C++17)

目录

参数

lhs, rhs - 待交换内容的元组

返回值

(无)

异常

noexcept 规范：
noexcept ( noexcept ( lhs. swap ( rhs ) ) )

示例

运行此代码 
#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): ");
}

输出： 

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}

另请参阅

交换两个 tuple 的内容
(公开成员函数)
(C++11)
特化 std::swap 算法
(函数模板)