unordered_multimap_name.emplace(key, element)

// C++程序示例
// unordered_multimap::emplace()
#include <iostream>
#include <string>
#include <unordered_map>
using namespace std;

int main()
{

    //声明
    unordered_multimap<int, int> sample;

    //插入“键”和“元素”
    sample.emplace(1, 2);
    sample.emplace(1, 2);
    sample.emplace(1, 3);
    sample.emplace(4, 9);
    sample.emplace(60, 89);

    cout << "键和元素：\n";
    for (auto it = sample.begin(); it != sample.end(); it++)
        cout << "{" << it->first << ":" << it->second << "}\n ";

    return 0;
}

键和元素：
 {60:89}
 {4:9}
 {1:3}
 {1:2}
 {1:2}

// unordered_multimap::emplace
#include <iostream>
#include <string>
#include <unordered_map>
using namespace std;

int main()
{

    //声明
    unordered_multimap<string, string> sample;

    //插入“键”和“元素”
    sample.emplace("gopal", "dave");
    sample.emplace("gopal", "dave");
    sample.emplace("Geeks", "C++");
    sample.emplace("multimap", "functions");
    sample.emplace("multimap", "functions");

    cout << "键和元素：\n";
    for (auto it = sample.begin(); it != sample.end(); it++)
        cout << "{" << it->first << ":" << it->second << "}\n ";

    return 0;
}

键和元素：
 {multimap:functions}
 {multimap:functions}
 {Geeks:C++}
 {gopal:dave}
 {gopal:dave}