智能指针

 1 template <typename T>
 2 class CSmartPtr
 3 {
 4 public:
 5     CSmartPtr(T* p = nullptr)
 6     {
 7         if (p != nullptr)
 8         {
 9             m_p = p;
10             m_pCnt = new int(1);
11         }
12     }
13     CSmartPtr(const CSmartPtr& ptr)
14     {
15         if (ptr.m_p == nullptr)
16         {
17             return;
18         }
19         m_p = ptr.m_p;
20         m_pCnt = ptr.m_pCnt;
21         ++(*m_pCnt);
22     }
23     ~CSmartPtr()
24     {
25         --(*m_pCnt);
26         if (*m_pCnt == 0)
27         {
28             delete m_p;
29             delete m_pCnt;
30         }
31         m_p = nullptr;
32         m_pCnt = nullptr;
33     }
34     CSmartPtr& operator=(const CSmartPtr& pT)
35     {
36         //1. 判断是不是自己
37         if (this == &pT)
38         {
39             return *this;
40         }
41         //2. 清理自身，减少引用计数
42         if (m_p != nullptr)
43         {
44             --(*m_pCnt);
45             if (*m_pCnt == 0)
46             {
47                 delete m_p;
48                 delete m_pCnt;
49             }
50             m_p = nullptr;
51             m_pCnt = nullptr;
52         }
53         //3. 拷贝目标，增加引用计数
54         m_p = pT.m_p;
55         m_pCnt = pT.m_pCnt;
56         if (pT.m_pCnt != nullptr)
57         {
58             ++(*m_pCnt);
59         }
60 
61         return *this;
62     }
63     T* operator->()
64     {
65         return m_p;
66     }
67     T& operator*()
68     {
69         return *m_p;
70     }
71     //CFoo* Get(){return m_p;}
72 private:
73     T* m_p = nullptr;
74     int* m_pCnt = nullptr;
75 };