拷贝赋值移动

#include<iostream>
using namespace std;
class B
{
public:
    B()
    {
        cout << "B()被调用" << endl;
    }
    B(const B&)
    {
        cout << "B的拷贝构造函数被调用" << endl;
    }
    B& operator=(const B&)
    {
        cout << "B的赋值函数被调用" << endl;
        return *this;
    }
    B(B&&)
    {
        cout << "B的移动构造函数被调用" << endl;
    }
    B& operator=(B&&)
    {
        cout << "B的移动赋值被调用" << endl;
        return *this;
    }
    ~B()
    {
       
    }
};
class A
{
private:
    string *str;
    B b;
public:
    A(const string& c = string()) :str(new string(c)){ cout << "构造函数被调用" << endl;}
    A(const A& another) :str(new string(*another.str)),b(another.b) { cout << "拷贝构造被调用" << endl;}
    A& operator=(const A& another)
    {
        cout << "赋值函数被调用" << endl;
        b = another.b;
        string *temp = new string(*another.str);
        delete str;
        str = temp;
        return *this;
    }
    A(A&&another)
    {
        cout << "移动构造被调用" << endl;
        str = another.str;
        another.str = nullptr;
        b = std::move(another.b);
    }
    A& operator=(A&&another)
    {
        cout << "移动赋值函数被调用" << endl;
        if (this!=&another)
        {
            delete str;
            str = another.str;
            another.str = nullptr;
            b = std::move(another.b);
        }
        return *this;
    }
    ~A()
    {
        delete str;
    }
};

A foo()
{
    return A();
}
int main()
{

//测试一:
    A a;
    A b;
    b = std::move(a);
    cout << "-------------" << endl;
//测试二
    A a1;
    A b2(std::move(a1));
    return 0;
}

输出: