【c++】智慧指標

// vc下的智慧指標，重點在於擁有權的轉移

#include <iostream>
using namespace std;

template<class Type>
class Autoptr
{
public:
	Autoptr(int *p = NULL) :ptr(p), owns(ptr != NULL)
	{}
	Autoptr(const Autoptr<Type> &t) :ptr(t.release()), owns(t.owns)
	{}
	Autoptr<Type>& operator=(const Autoptr<Type> &t)
	{
		if (this != &t)// 判斷是否給自己賦值
		{
			if (ptr != t.ptr)// 判斷是否指向同一個空間
			{
				if (owns)// 如果有擁有權，則釋放當前空間
				{
					delete ptr;
				}
				else
				{
					owns = t.owns;// 反之，得到擁有權
				}
				ptr = t.release();// 讓t失去擁有權
			}
		}
		return *this;
	}
	~Autoptr()
	{
		if (owns)
			delete ptr;
	}
public:
	Type& operator*()const
	{
		return (*get());
	}
	Type* operator->()const
	{
		return get();
	}
	Type* get()const
	{
		return ptr;
	}
	Type* release()const
	{
		((Autoptr<Type> *const)this)->owns = false;
		return ptr;
	}
private:
	bool owns;
	Type *ptr;
};

int main()
{
	int *p = new int(10);
	Autoptr<int> pa(p);
	cout << *pa << endl;
	Autoptr<int> pa1(pa);
	cout << *pa1 << endl;
	int *p1 = new int(100);
	Autoptr<int> pa2(p1);
	Autoptr<int> pa3;
	pa3 = pa2;
	cout << *pa3 << endl;
	return 0;
}