SharePtr的簡單實現

#include <iostream>
#include<string>
using namespace std;
#pragma warning(disable:4996)
template<class T, class Del>
class SharePtr
{
public:
    SharePtr(T* ptr) //建構函式
        :_ptr(ptr), _ref(new int(1))
    {
        cout << "SharePtr(T* ptr) " << endl;
    }
    SharePtr(SharePtr& cp)//拷貝建構函式
 

    {
        cout << "SharePtr(SharePtr& cp)" << endl;
        _ptr = cp._ptr;
        _ref = cp._ref;
        (*_ref)++;
    }
    ~SharePtr()//解構函式 
    {
        Release();
    }
    void Release()
    {
        if (--(*_ref) == 0)
        {
            delete _ref;
            _del(_ptr);
        }
    }
    T* operator
 
->()//->操作符過載
    {
        return _ptr;
    }
    T& operator*()//解引用操作符過載
    {
        return *_ptr;
    }
    SharePtr& operator=(SharePtr& sp)//賦值操作符過載
    {
        if (_ptr != sp._ptr)
        {
            Release();
            _ptr = sp._ptr;
            _ref = sp._ref;
            (*_ref)++;
        }
        return
 
 *this;
    }

private:
    T* _ptr;
    int* _ref;
    Del _del;//這是一個物件函式決定著析構時以什麼方式釋放申請的空間
};
//以上為class SharePtr的內容
template<class T>
struct Delete
{
    void operator()(T* ptr)
    {
        cout << "delete" << endl;
        delete ptr;
    }
};
template<class T>
struct DeleteArr
{
    void operator()(T* ptr)
    {
        cout << "delete[]" << endl;
        delete[] ptr;
    }
};
template<class T>
struct Free
{
    void operator()(T* ptr)
    {
        cout << "free" << endl;
        free(ptr);
    }
};
template<class T>
struct Close
{
    void operator()(T* ptr)
    {
        cout << "close" << endl;
        if (ptr != NULL)
        {
            fclose(ptr);
        }
    }
};
//以上為物件函式
//下面為主函式程式碼
int main()
{
    SharePtr<int, Delete<int>>  p1(new int(10));
    SharePtr<int, Delete<int>> p2(p1);
    SharePtr<string, DeleteArr<string>>  p3(new string[3]);
    SharePtr<string, DeleteArr<string>> p4(p3);
    SharePtr<string, DeleteArr<string>> p5(p4);
    SharePtr<int, Delete<int>> p6(new int(20));
    SharePtr<int, Free<int>> p7 = (int*)malloc(sizeof(int));
    SharePtr<FILE, Close<FILE>> p8 = fopen("FILENAME", "r");

    cout << *p1 << "," << *p2 << endl;
    p2 = p6;
    *p1 = 15;
    cout << *p1 << "," << *p2 << endl;
    return 0;
}

結果為