c++ stl

#include 
#include 
using namespace std;
int main() {
    unordered_map m {
        {"apple", 1},
        {"banana", 2}
    };
    printf("%dn", m["banana"]);  //2
    m.insert({"pear", 3});
    printf("%dn", m["pear"]);    //3
    printf("%dn", m["xxxxx"]);   //0
    for (auto it = m.begin(); it != m.end(); it++) {
        printf("%s: %dn", it->first.c_str(), it->second);
    }
    //xxxxx: 0
    //pear: 3
    //apple: 1
    //banana: 2
    printf("n");
    auto it = m.find("banana");
    printf("%s: %dn", it->first.c_str(), it->second);//banana:2
    m.erase("banana");
    for (auto it = m.begin(); it != m.end(); it++) {
        printf("%s: %dn", it->first.c_str(), it->second);
    }
    //xxxxx: 0
    //pear: 3
    //apple: 1
    return 0;
}