C++实现简单的智能指针

/*
    智能指针的简单实现
*/

template<typename T>
class SamrtPtr
{
public:
    //构造函数
    SamrtPtr(T* ptr = nullptr) :m_ptr(ptr) {
        if (m_ptr) {
            m_count = new size_t(1);
        }
        else {
            m_count = new size_t(0);
        }
    }

    //拷贝构造函数
    SamrtPtr(const SamrtPtr&that)
    {
        if (this != &that) {
            this->m_ptr = that.m_ptr;
            //指针指向的实际上是同一个计数器，同一块内存
            this->m_count = that.m_count;
            (*this->m_count)++;
        }
    }

    //拷贝赋值函数
    SamrtPtr&operator=(const SamrtPtr&that)
    {
        //指针指向的实际上是同一个计数器，同一块内存
        if (this->m_ptr == that.m_ptr)
        {
            return *this;
        }

        if (this->m_ptr)
        {
            //将原来的引用计数减一
            (*this->_count)--;
            if (this->_count == 0) {
                delete this->_ptr;
                delete this->_count;
            }
        }

        this->m_ptr = that.m_ptr;
        this->m_count = that.m_count;
        (*this->m_count)++;
        return *this;
    }

    //重载*操作符
    T& operator*()
    {
        return *(this->m_ptr);
    }

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

    ~SamrtPtr()
    {
        (*this->m_count)--;
        if (*this->m_count == 0)
        {
            delete this->m_ptr;
            delete this->m_count;
        }
    }

    size_t use_count() {
        return *this->m_count;
    }

private:
    //指针
    T* m_ptr;
    //计数器
    size_t* m_count;
};