C++11标准模板（STL）- 算法（std::iter_swap）

定义于头文件 

算法库提供大量用途的函数（例如查找、排序、计数、操作），它们在元素范围上操作。注意范围定义为 [first, last) ，其中 last 指代要查询或修改的最后元素的后一个元素。

交换两个迭代器所指向的元素

std::iter_swap

交换给定的迭代器所指向的元素的值。

参数

返回值

（无）

复杂度

常数

 可能的实现

template<class ForwardIt1, class ForwardIt2>
constexpr void iter_swap(ForwardIt1 a, ForwardIt2 b) // C++20 起为 constexpr
{
   using std::swap;
   swap(*a, *b);
}

调用示例

#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <vector>
#include <list>
 
struct Cell
{
    int x;
    int y;
    Cell &operator+=(Cell &cell)
    {
        x += cell.x;
        y += cell.y;
        return *this;
    }
};
 
std::ostream &operator<<(std::ostream &os, const Cell &cell)
{
    os << "{" << cell.x << "," << cell.y << "}";
    return os;
}
 
int main()
{
    auto func1 = []()
    {
        static Cell cell = {99, 100};
        cell.x += 2;
        cell.y += 2;
        return cell;
    };
 
    std::vector<Cell> cells_1(6);
    std::generate_n(cells_1.begin(), cells_1.size(), func1);
    std::list<Cell> cells_2(8);
    std::generate_n(cells_2.begin(), cells_2.size(), func1);
 
    std::cout << "original : " << std::endl;
    std::cout << "cells_1 : ";
    std::copy(cells_1.begin(), cells_1.end(), std::ostream_iterator<Cell>(std::cout, " "));
    std::cout << std::endl;
    std::cout << "cells_2 : ";
    std::copy(cells_2.begin(), cells_2.end(), std::ostream_iterator<Cell>(std::cout, " "));
    std::cout << std::endl << std::endl;
 
    auto it1 = cells_1.begin();
    auto it2 = cells_2.begin();
    for (; it1 != cells_1.end(); it1++, it2++)
    {
        std::iter_swap(it1, it2);
    }
 
    std::cout << "new : " << std::endl;
    std::cout << "cells_1 : ";
    std::copy(cells_1.begin(), cells_1.end(), std::ostream_iterator<Cell>(std::cout, " "));
    std::cout << std::endl;
    std::cout << "cells_2 : ";
    std::copy(cells_2.begin(), cells_2.end(), std::ostream_iterator<Cell>(std::cout, " "));
    std::cout << std::endl << std::endl;
}

输出