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std:: swap (std::map)

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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 = [](std::pair<const int, char>& n)
    {
        std::cout << ' ' << n.first << ':' << n.second;
    };
    // 交换前的状态输出
    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);
    // 交换后的状态输出
    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
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