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    std:: swap (std::map)

    From zh.cppreference.net

    C++
    Containers library
    std::map
    Member functions
    Non-member functions
    (C++20)
    std::swap (std::map)
    (C++20)

    (until C++20) (until C++20) (until C++20) (until C++20) (until C++20)
    Deduction guides (C++17)
    定义于头文件 <map>
    template < class Key, class T, class Compare, class Alloc >

    void swap ( std:: map < Key, T, Compare, Alloc > & lhs,

    std:: map < Key, T, Compare, Alloc > & rhs ) ;
    		(C++17 前)
    template < class Key, class T, class Compare, class Alloc >

    void swap ( std:: map < Key, T, Compare, Alloc > & lhs,
    std:: map < Key, T, Compare, Alloc > & rhs )

    noexcept ( /* 见下文 */ ) ;
    		(C++17 起)
    (C++26 起为 constexpr)

    为 std::swap 算法针对 std::map 进行特化。交换 lhs 和 rhs 的内容。调用 lhs. swap ( rhs ) 。

    目录

    参数

    lhs, rhs - 要交换内容的容器

    复杂度

    常量。

    异常处理

    noexcept 规范：
    noexcept ( noexcept ( lhs. swap ( rhs ) ) )
    		(自 C++17 起)

    示例

    运行此代码
    #include <algorithm>
#include <iostream>
#include <map>

int main()
{
    std::map<int, char> alice{{1, 'a'}, {2, 'b'}, {3, 'c'}};
    std::map<int, char> bob{{7, 'Z'}, {8, 'Y'}, {9, 'X'}, {10, 'W'}};

    auto print = [](const std::pair<int, char>& n)
    {
        std::cout << ' ' << n.first << ':' << n.second;
    };

    // Print state before swap
    std::cout << "Alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\nBobby:";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';

    std::cout << "-- SWAP\n";
    std::swap(alice, bob);

    // Print state after swap
    std::cout << "Alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\nBobby:";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';
}

    输出：

    Alice: 1:a 2:b 3:c
Bobby: 7:Z 8:Y 9:X 10:W
-- SWAP
Alice: 7:Z 8:Y 9:X 10:W
Bobby: 1:a 2:b 3:c

    另请参阅

    		交换内容
    (公开成员函数)