c++中map如何遍历和删除元素_c++ map容器的遍历与安全删除技巧

std::map<int, std::string> myMap = {{1, "one"}, {2, "two"}, {3, "three"}};

for (auto it = myMap.begin(); it != myMap.end(); ++it) {
    std::cout << it->first << ": " << it->second << std::endl;
}

for (const auto& pair : myMap) {
    std::cout << pair.first << ": " << pair.second << std::endl;
}

for (auto it = myMap.begin(); it != myMap.end();) {
    if (shouldRemove(it->first)) {  // 假设根据键判断是否删除
        it = myMap.erase(it);       // erase 返回下一个有效的迭代器
    } else {
        ++it;
    }
}

std::vector<int> keysToRemove;
for (const auto& pair : myMap) {
    if (shouldRemove(pair.first)) {
        keysToRemove.push_back(pair.first);
    }
}
for (int key : keysToRemove) {
    myMap.erase(key);
}

for (auto rit = myMap.rbegin(); rit != myMap.rend(); ) {
    if (shouldRemove(rit->first)) {
        rit = std::map<int, std::string>::reverse_iterator(myMap.erase(std::next(rit).base()));
    } else {
        ++rit;
    }
}