C++结构和std:vector元素之间的别名--为什么？

typedef struct {
    int id;
    std::string name;
    int age;
} Person;

typedef std::vector<int> IntVector;

int main() {
    Person p;
    p.id = 1;
    p.name = "John";
    p.age = 30;

    IntVector numbers;
    numbers.push_back(1);
    numbers.push_back(2);
    numbers.push_back(3);

    // 使用别名操作结构和std::vector元素
    std::cout << "Person name: " << p.name << std::endl;
    std::cout << "First number: " << numbers[0] << std::endl;

    return 0;
}

struct Person {
    int id;
    std::string name;
    int age;
};

using IntVector = std::vector<int>;

int main() {
    Person p;
    p.id = 1;
    p.name = "John";
    p.age = 30;

    IntVector numbers;
    numbers.push_back(1);
    numbers.push_back(2);
    numbers.push_back(3);

    // 使用别名操作结构和std::vector元素
    std::cout << "Person name: " << p.name << std::endl;
    std::cout << "First number: " << numbers[0] << std::endl;

    return 0;
}