面试实现智能指针

#include<iostream>
#include<cstdio>
using namespace std;
template<typename T> 
class SmartPointer
{
public:
	SmartPointer(T* ptr)
	{
		ref=ptr;
		ref_count=(unsigned int*) malloc(sizeof(unsigned));
		*ref_count=1;
	}
	SmartPointer(const SmartPointer<T>& other)
	{
		ref=other.ref;
		ref_count=other.ref_count;
		++*ref_count;
	}
	SmartPointer& operator=(SmartPointer<T>& other)
	{
		if(this==&other)
			return *this;
		if(--*ref_count==0)
		{
			clear();
		}
		ref=other.ref;
		ref_count=other.ref_count;
		++*ref_count;

		return *this;
	}
	T& operator*()
	{
		return *ref;
	}
	T* operator->()
	{
		return ref;
	}
	~SmartPointer()
	{
		if(--*ref_count==0)
		{
			clear();
		}

	}
private:
	void clear()
	{
		delete ref;
		free(ref_count);
		ref=NULL;
		ref_count=NULL;
	}
protected:
	T* ref;
	unsigned int* ref_count;
};

void main()
{
	
	int* p=new int();
	*p=11;
	SmartPointer<int> ptr1(p);
	SmartPointer<int> ptr2=ptr1;
	*ptr1=1;
	cout<<*ptr1<<" "<<*ptr2<<endl;
}