一个简单的智能指针的实现

#include<iostream>
#include<memory>

using namespace std;
template<typename T>
class SmartPtr {

public:
	SmartPtr(T *p = NULL) :_ptr(p) {
		if (_ptr)_count = new size_t(1);
		else
			_count = new size_t(0);
	}

	SmartPtr(const SmartPtr& p) {
		if (this != &p) {
			this->_ptr = p._ptr;
			this->_count = p._count;
			(*this->_count)++;
		}
	}


	SmartPtr& operator=(const SmartPtr& p)
	{
		++*p._count;
		if (--*_count == 0) {
			delete _count;
			delete _ptr;
		}
		this->_ptr = p._ptr;
		this->_count = p._count;
		return *this;
	}

	T &operator*() {
			return *(this->_ptr);
	}

	T *operator->() {
			return this->_ptr;
	}

	~SmartPtr()
	{
		
		if (--*_count == 0) {
			delete _ptr;
			delete _count;
		}
	}

	size_t use_count()
	{
		return *this->_count;
	}
private:
	T* _ptr;
	size_t *_count;
};