Again about rvalues

You can use rvalues for creating move semantics - remove copy constructors for temporaries. Example:

#include <iostream>

class A
{
public:
    A()
    {
        x = new int[1];
        x[0] = 1;
        std::cout << "new\n";
    }
    ~A()
    {
        delete[] x;
    }

    A(const A& a)
    {
        x = new int[1];
        x[0] = a.x[0];
        std::cout << "new\n";
    }

   /* A(A&& a) //move constructor
    {
        x = a.x;
        a.x = 0;
    }*/
private:
    int *x;
};

A GetA()
{
    A a;
    return a;
}

//if you want to use movable object as member in another object you should declare move constructor
//and use std::move
class B
{
public:
    B(){}
    B(B&& b) //move constructor
    {
        a = std::move(b.a);
    }
    A a;
};

B GetB()
{
    B b;
    return b;
}

int main(int, char*[])
{
    B b = GetB();
    {
        A a = GetA();
        A a2(a);
        std::cout << "scope\n";
    }
    return 0;
}