# std::pair

他的實作很簡單，幾乎跟我下面的實作一樣，只是他多了swap()跟比較運算子 < <= > => == != operator overlading，讓pair可以互相比較，先比較key再比較value

[C++ STL pair用法详解 - C语言中文网](https://c.biancheng.net/view/7169.html)

#include <utility>
#include <iostream>
#include <string>

template <typename T1, typename T2>
class Pair {
public:
    Pair() : first(T1()), second(T2()) {}
    Pair(T1 first, T2 second) : first(first), second(second) {}
    
    T1 first;
    T2 second;
};


int main() {
    Pair<std::string, int> my_pair("my_pair1", 1);
    std::cout << my_pair.first << " " << my_pair.second << std::endl;


    std::pair <std::string, int> pair1("pair1", 1);
    std::cout << pair1.first << " " << pair1.second << std::endl;
    return 0;
}