如何使用BOOST_FOREACH和两个std :: maps？

#include<boost/foreach.hpp>
#include <map>

std::map<int, std::string> map1;
map1[1] = "one";
map1[2] = "two";
map1[3] = "three";

std::map<int, double> map2;
map2[1] = 1.1;
map2[2] = 2.2;
map2[3] = 3.3;

BOOST_FOREACH(const std::pair<int, std::string>& p1, map1) {
    std::cout << "Key: " << p1.first << ", Value: " << p1.second<< std::endl;

    std::map<int, double>::iterator it2 = map2.find(p1.first);
    if (it2 != map2.end()) {
        std::cout << "Key: " << it2->first << ", Value: " << it2->second<< std::endl;
    }
}

for (const auto& p1 : map1) {
    std::cout << "Key: " << p1.first << ", Value: " << p1.second<< std::endl;

    auto it2 = map2.find(p1.first);
    if (it2 != map2.end()) {
        std::cout << "Key: " << it2->first << ", Value: " << it2->second<< std::endl;
    }
}