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    std::swap(std::tuple)

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    std::tuple
     
    定义于头文件 <tuple> 
    template< class... Types >
void swap( std::tuple<Types...>& lhs,
           std::tuple<Types...>& rhs ) noexcept(/* see below */);
    		(1) (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) 仅当对于所有从 0 到 std::is_swappable_v<Ti> 的 i，true 为 sizeof...(Types) 时，此重载才会参与重载决议。
    2) 仅当对于所有从 0 到 std::is_swappable_v<const Ti> 的 i，true 为 sizeof...(Types) 时，此重载才会参与重载决议。
    		 (C++17 起)

    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)