weak_ptr解相互引用

- 日理万妓 2022-10-17 00:36 191阅读 0赞

具体参考：[https://blog.csdn.net/albertsh/article/details/82286999][https_blog.csdn.net_albertsh_article_details_82286999]

#include <vector> 
    #include <iostream> 
    #include <memory>
    
    using namespace std;
    
    class CB;
    class CA
    {
    public:
        CA() { cout << "CA() called! " << endl; }
        ~CA() { cout << "~CA() called! " << endl; }
        void set_ptr(shared_ptr<CB>& ptr) { m_ptr_b = ptr; }
        void b_use_count() { cout << "b use count : " << m_ptr_b.use_count() << endl; }
        void show() { cout << "this is class CA!" << endl; }
    private:
        shared_ptr<CB> m_ptr_b;
    };
    
    class CB
    {
    public:
        CB() { cout << "CB() called! " << endl; }
        ~CB() { cout << "~CB() called! " << endl; }
        void set_ptr(shared_ptr<CA>& ptr) { m_ptr_a = ptr; }
        void a_use_count() { cout << "a use count : " << m_ptr_a.use_count() << endl; }
        void show() { cout << "this is class CB!" << endl; }
    private:
        //weak_ptr<CA> m_ptr_a; //情况2
        shared_ptr<CA> m_ptr_a; //情况一
    };
    
    void test_refer_to_each_other()
    {
        shared_ptr<CA> ptr_a(new CA());
        shared_ptr<CB> ptr_b(new CB());
    
        cout << "a use count : " << ptr_a.use_count() << endl;
        cout << "b use count : " << ptr_b.use_count() << endl;
    
        ptr_a->set_ptr(ptr_b);
        ptr_b->set_ptr(ptr_a);
    
        cout << "a use count : " << ptr_a.use_count() << endl;
        cout << "b use count : " << ptr_b.use_count() << endl;
        return;
    }
    
    
    int main() {
        test_refer_to_each_other();
        return 0;
    }

情况一输出：

![20210531143303922.png][]

情况二输出：

![20210531143349503.png][]

[https_blog.csdn.net_albertsh_article_details_82286999]: https://blog.csdn.net/albertsh/article/details/82286999
[20210531143303922.png]: /images/20221014/15cea14d44e946509ebdcf742a9368f5.png
[20210531143349503.png]: /images/20221014/dc25c5c7d30f4f6890101a14c53d2212.png