实现类似shared_ptr的引用计数

#include<iostream>
#include<string>
#include<new>

using namespace std;
class HasPtr
{
public:
    HasPtr(const string &s=string()):ps(new string(s)),i(0),use(new size_t(1)) {cout<<"constructer"<<endl;}
    HasPtr(const HasPtr &h):i(h.i)
    {
        cout<<"copy constructer"<<endl;
        ps=h.ps;
        ++*h.use;
        use=h.use;
    }
    HasPtr& operator=(const HasPtr &h)
    {
        ++*h.use;
        //将原来分配的内存空间删除
        while(--*use==0)
        {
            delete ps;
            delete use;
        }
        //指向新的内存空间
        ps=h.ps;
        i=h.i;
        use=h.use;
        return *this;
    }
    //如果在赋值操作中删除了左边对象的内存空间，则此处调用析构函数时将不再删除内存空间，但是该对象还是会被析构
    ~HasPtr()
    {
        if(--*use==0)
        {
            delete ps;
            delete use;
        }
        cout<<"destructer"<<endl;
    }
private:
    string *ps;
    int i;
    size_t *use;
};
int main()
{
    HasPtr h;
    HasPtr hh(h);
    hh=h;
    return 0;
}