在std :: map中引用为键

#include<iostream>
#include <map>

int main() {
    std::map<int, std::string> my_map;
    my_map[1] = "one";
    my_map[2] = "two";
    my_map[3] = "three";

    int key = 2;
    auto it = my_map.find(key);
    if (it != my_map.end()) {
        std::cout << "Key "<< key << " found, value: " << it->second<< std::endl;
    } else {
        std::cout << "Key "<< key << " not found"<< std::endl;
    }

    return 0;
}