c++ STL swap用法和实现

一：功能

交换两个值

二：用法

#include <format>
#include <iostream>

namespace Library {
struct Storage {
	int value;
};

//支持swap操作
void swap(Storage& left, Storage& right) {
	std::ranges::swap(left.value, right.value);
}
}

int main() {
	int a = 1, b = 2;
	std::ranges::swap(a, b); // 3-step-swap
    
    std::format_to(std::ostreambuf_iterator(std::cout),
        "a == {}, b == {}\n", a, b);

	Library::Storage j{2}, k{3};
	std::ranges::swap(j, k); // calls custom Library::swap()

    std::format_to(std::ostreambuf_iterator(std::cout),
        "j == {}, k == {}\n", j.value, k.value);
}

三：实现

#include <algorithm>
#include <iostream>
  
template<typename T>
void my_swap(T &a,T &b) noexcept
{
    T temp = std::move(a);
    a = std::move(b);
    b = std::move(temp);
}

int main()
{
    int a = 5, b = 3;
    std::cout << a << ' ' << b << '\n';
    my_swap(a, b);
    std::cout << a << ' ' << b << '\n';
}