c++ 遍历map，获取其中的key

以下是C++遍历map并获取其中的key的两种方式：

1. 使用迭代器遍历map并获取key：

#include <iostream>
#include <map>

int main() {
    std::map<int, std::string> myMap;
    myMap[1] = "apple";
    myMap[2] = "banana";
    myMap[3] = "orange";

    // 使用迭代器遍历map并获取key
    for (std::map<int, std::string>::iterator it = myMap.begin(); it != myMap.end(); ++it) {
        int key = it->first;
        std::cout << "Key: " << key << std::endl;
    }

    return 0;
}

2. 使用C++11的范围-based for循环遍历map并获取key：

#include <iostream>
#include <map>

int main() {
    std::map<int, std::string> myMap;
    myMap[1] = "apple";
    myMap[2] = "banana";
    myMap[3] = "orange";

    // 使用C++11的范围-based for循环遍历map并获取key
    for (const auto& pair : myMap) {
        int key = pair.first;
        std::cout << "Key: " << key << std::endl;
    }

    return 0;
}