auto_ptr、shared_ptr、unique_ptr 几句代码你就懂了

#include<iostream>

#include <memory>

int main()

{

        auto_ptr<int> p(new int(9));

        auto_ptr<int> ap = p;

        //cout<<*p<<endl;//错误：p权限已转交无法访问到了原先指向的内存区域中的数据

         unique_ptr<int> utemp(new int(9));

        unique_ptr<int> up;

        //up = utemp;   //错误!同一块内存只能用一个指针指向

         shared_ptr<int> stemp(new int(9));

        shared_ptr<int> sp;

        sp = stemp;

        sp = stemp;     //再次指向同一块内存引用计数不变

         {

        shared_ptr<int> mp = stemp;

        cout<<sp.use_count()<<endl;//输出3

        }               //mp释放掉以后以用计数减去1

        cout<<sp.use_count()<<endl;//输出2

        return 1;

}