C++ STL pair

#include 
#include 
#include 

using namespace std;


void pairConstructor(){

    // 调用构造函数 1，也就是默认构造函数
    pair  pair1;
    pair1.first = "hello";
    pair1.second = 1.25;
    // 调用第 2 种构造函数
    pair  pair2("STL教程","http://c.biancheng.net/stl/");  
    // 调用拷贝构造函数
    pair  pair3(pair2);
    //调用移动构造函数
    pair  pair4(make_pair("C++教程", "http://c.biancheng.net/cplus/"));
    // 调用第 5 种构造函数
    pair  pair5(string("Python教程"), string("http://c.biancheng.net/python/"));  
   
    cout << "pair1: " << pair1.first << " " << pair1.second << endl;
    cout << "pair2: "<< pair2.first << " " << pair2.second << endl;
    cout << "pair3: " << pair3.first << " " << pair3.second << endl;
    cout << "pair4: " << pair4.first << " " << pair4.second << endl;
    cout << "pair5: " << pair5.first << " " << pair5.second << endl;
}

void pairCompare(){
    pair  pair1("STL教程", 20);
    pair  pair2("C++教程", 20);
    pair  pair3("C++教程", 30);
    //pair1和pair2的key不同，value相同
    if (pair1 != pair2) {
        cout << "pair != pair2" << endl;
    }
    //pair2和pair3的key相同，value不同
    if (pair2 != pair3) {
        cout << "pair2 != pair3" << endl;
    }
}

int main(){
    pairConstructor();
    pairCompare();
    return 0;
}