C++在不知道大小的情况下检测悬空指针

#include<iostream>
#include<memory>

int main() {
    std::shared_ptr<int> ptr1(new int(10));
    std::shared_ptr<int> ptr2 = ptr1;

    std::cout << "ptr1 use_count: "<< ptr1.use_count()<< std::endl;
    std::cout << "ptr2 use_count: "<< ptr2.use_count()<< std::endl;

    ptr1.reset();

    std::cout << "ptr1 use_count: "<< ptr1.use_count()<< std::endl;
    std::cout << "ptr2 use_count: "<< ptr2.use_count()<< std::endl;

    return 0;
}