C++中based for循环的实现

for (declaration : container) {
    // 循环体
}

#include <iostream>

int main() {
    int arr[] = {1, 2, 3, 4, 5};

    // 使用范围基 for 循环遍历数组
    for (int num : arr) {
        std::cout << num << " ";
    }

    return 0;
}

#include <iostream>
#include <vector>

int main() {
    std::vector<int> vec = {10, 20, 30, 40, 50};

    // 使用范围基 for 循环遍历 std::vector
    for (int num : vec) {
        std::cout << num << " ";
    }

    return 0;
}

#include <iostream>
#include <vector>

class Person {
public:
    std::string name;
    Person(std::string n) : name(n) {}
};

int main() {
    std::vector<Person> people = {Person("Alice"), Person("Bob"), Person("Charlie")};

    // 使用引用避免拷贝
    for (Person& p : people) {
        std::cout << p.name << " ";
    }

    return 0;
}

#include <iostream>
#include <vector>

int main() {
    std::vector<int> vec = {1, 2, 3, 4, 5};

    // 使用常量引用，避免拷贝且不修改元素
    for (const int& num : vec) {
        std::cout << num << " ";
    }

    return 0;
}

#include <iostream>
#include <map>

int main() {
    std::map<int, std::string> m = {{1, "One"}, {2, "Two"}, {3, "Three"}};

    // 遍历 map（键值对）
    for (const auto& pair : m) {
        std::cout << "Key: " << pair.first << ", Value: " << pair.second << std::endl;
    }

    return 0;
}