day7 c++

整理代码

1、unique_ptr 指针

#include <iostream>
#include <memory>
using namespace std;
class Demo
{

public:
    Demo(){cout<<"无参构造"<<endl;}
    ~Demo(){cout<<"Demo的析构函数"<<endl;}
};

int main()
{
    //unique_ptr指针
    //1、使用堆空间进行初始化
    unique_ptr<Demo> p1(new Demo);
    cout<<p1.get()<<endl;

    //2、使用原始指针进行初始化
    Demo *p = new Demo;
    cout << p<<endl;
    unique_ptr<Demo> p2(p);
    cout <<"p2="<<p2.get()<<endl;
    //swap交换
    swap(p1,p2);
    cout <<"交换后:"<<"p1="<<p1.get()<<"\n"<<"p2="<<p2.get()<<endl;

    //3、使用函数初始化
    unique_ptr<Demo> p3=make_unique<Demo>();
    p3=nullptr;
    cout<<"p3="<<p3.get()<<endl;

    unique_ptr<Demo> p4;
    //4、想要P4独占P2指向的空间   move函数(智能指针)
    p4=move(p2);
    cout<<"p2="<<p2.get()<<endl;
    cout<<"p4="<<p4.get()<<endl;

    //释放p4对空间的所有权  返回首地址
    Demo *test=p4.release();
    cout <<"p4="<<p4.get()<<endl;
    cout <<"test="<<test<<endl;

    p4.reset();  //调用析构函数  释放空间所有权，释放堆区空间
    cout << "p4="<<p4.get()<<endl;

    return 0;
}

2、共享指针和弱智能指针共用

#include <iostream>
#include <memory>

//使用weak和share解决循环引用
using namespace std;
class Test;
class Demo
{
public:
    weak_ptr<Test> t;
    Demo(){cout <<"无参构造"<<endl;}
    ~Demo(){cout << "Demo的析构" << endl;}
};

class Test
{
public:
    weak_ptr<Demo> d;
    Test(){cout << "Test的无参构造" << endl;}
    ~Test(){cout << "Test的析构" << endl;}
};
int main()
{
    shared_ptr<Demo> p1(new Demo);
    shared_ptr<Test> p2(new Test);
    p1->t=p2;
    p2->d=p1;
    cout <<"p1的计数="<<p1.use_count()<<endl;
    cout <<"p2的计数="<<p2.use_count()<<endl;
    weak_ptr<Demo> p3(p1);
    cout <<"p1计数="<<p1.use_count()<<endl;

    return 0;
}

2、思维导图