What the Source Owns After a Move

1#include <iostream>
2#include <utility>
3using namespace std;
4 
5class Buffer {
6    int* m_data;
7    int m_size;
8public:
9    Buffer(int size) : m_size(size) {
10        m_data = new int[size];
11        for (int i = 0; i < size; i++) {
12            m_data[i] = i * 10;
13        }
14    }
15    Buffer(Buffer&& other) noexcept {
16        m_data = other.m_data;
17        m_size = other.m_size;
18        other.m_data = nullptr;
19        other.m_size = 0;
20    }
21    ~Buffer() { delete[] m_data; }
22    int size() const { return m_size; }
23    bool empty() const { return m_data == nullptr; }
24    int at(int i) const { return m_data[i]; }
25};
26 
27int main() {
28    Buffer a(3);
29    cout << a.size() << " " << a.empty() << endl;
30    Buffer b(std::move(a));
31    cout << b.size() << " " << b.at(2) << endl;
32    cout << a.size() << " " << a.empty() << endl;
33    return 0;
34}