#include <iostream>
using namespace std;

class A
{
    size_t n; 
    double *x;
public:
    double & operator[](int i) { return x[i]; }
    const double & operator[](int i) const { return x[i]; }
    size_t Size() const { return n; }

    A(size_t nn) { 
        n = nn;  
        x = new double[nn]; 
        cout << "base A()\n"; 
    }
    A(const A & b) { 
        x = new double[b.n]; 
        n = b.n;  
        for (size_t i = 0; i < n; i++) x[i] = b.x[i];
        cout << "copy A()\n"; 
    }
    A(A &&b) { 
        x = b.x; 
        n = b.n; 
        b.x = nullptr;
        b.n = 0;  
        cout << "move A()\n"; 
    }
    const A & operator=(const A& b) { 
        delete [] x;
        x = new double[b.n];
        n = b.n; 
        for (size_t i = 0; i < n; i++) x[i] = b.x[i];
        cout << "copy =\n"; 
        return *this; 
    }
    const A & operator=(A&& b) {
        int m = n; n = b.n; b.n = m; 
        double *p = x; x = b.x; b.x = p; 
        cout << "move =\n"; return *this;  
    }
//    A operator+(const A &b) const { 
//        A s(n); 
//        for (size_t i = 0; i < n && i < b.n; i++) s[i] = x[i] + b.x[i]; 
//        return s;
//    }

friend  A operator+(const A &a, const A &b); 
friend  ostream & operator<<(ostream &os, const A &a);
};

A operator+(const A &a, const A &b) 
{ 
        A s(a.n); 
        for (size_t i = 0; i < a.n && i < b.n; i++) s[i] = a[i] + b[i]; 
        return s;
}
ostream & operator<<(ostream &os, const A &a)
{
    os << "A: ";
    for (size_t i = 0; i < a.n; i++) os << " " << a[i];
    os << endl;
    return os;
} 

int main()
{
    A a(3);     
    a[0] = a[1] = a[2] = 1;
    cout << "a " << a;

    A b(3);     
    b[0] = b[1] = b[2] = 2;
    cout << "b " << b;

    A c(a);
    cout << "c " << c;

    cout << "A d(move(a)) ------------\n";
    A d(move(a));
    cout << "d " << d;
    cout << "a " << a;

    cout << "c = b   ------------\n";
    c = b;
    cout << "b " << b;
    cout << "c " << c;

    cout << "b = c + d ------------\n";
    b = c + d;
    cout << "b " <<  b;
    cout << "c " <<  c;
    cout << "d " <<  d;

    cout << "c = move(b) ------------\n";
    c = move(b);
    cout << "b " <<  b;
    cout << "c " <<  c;

    cout << "A f(b + c); ------------\n";
    A f(b + c);
    cout << "f " <<  f;
    cout << "b " <<  b;
    cout << "c " <<  c;

    return 0;   
}