在一个类方法中，两个`unordered_set`s在C++中的交集“不工作”，但与`set`一起工作？

#include <iostream>
#include <unordered_set>
#include <set>
#include <algorithm>
#include <vector>

class MyClass {
public:
    void intersection() {
        std::unordered_set<int> set1 = {1, 2, 3, 4, 5};
        std::unordered_set<int> set2 = {4, 5, 6, 7, 8};

        // 使用set代替unordered_set进行交集操作
        std::set<int> intersectionSet;
        for (const auto& element : set1) {
            if (set2.count(element) > 0) {
                intersectionSet.insert(element);
            }
        }

        // 输出交集结果
        for (const auto& element : intersectionSet) {
            std::cout << element << " ";
        }
        std::cout << std::endl;
    }

    void intersectionWithSorting() {
        std::unordered_set<int> set1 = {1, 2, 3, 4, 5};
        std::unordered_set<int> set2 = {4, 5, 6, 7, 8};

        // 将unordered_set中的元素复制到vector中
        std::vector<int> vector1(set1.begin(), set1.end());
        std::vector<int> vector2(set2.begin(), set2.end());

        // 对vector进行排序
        std::sort(vector1.begin(), vector1.end());
        std::sort(vector2.begin(), vector2.end());

        // 使用set_intersection计算交集
        std::vector<int> intersectionVector;
        std::set_intersection(vector1.begin(), vector1.end(), vector2.begin(), vector2.end(), std::back_inserter(intersectionVector));

        // 输出交集结果
        for (const auto& element : intersectionVector) {
            std::cout << element << " ";
        }
        std::cout << std::endl;
    }
};

int main() {
    MyClass obj;
    obj.intersection();
    obj.intersectionWithSorting();

    return 0;
}