unique_ptr owns and moves

std::make_unique creates a Point on the heap and a owns it. std::move(a) transfers ownership to b: afterwards a is empty (nullptr) and b points at the same heap block. No copy of the Point is made.

When b goes out of scope at the end of main, it deletes the Point for you.

#include <iostream>
#include <memory>

struct Point {
    int x;
    int y;
};

int main() {
    auto a = std::make_unique<Point>(Point{3, 4});
    a->x = 30;
    std::unique_ptr<Point> b = std::move(a);
    bool a_empty = (a == nullptr);
    std::cout << b->x << " " << a_empty << "\n";
    return 0;
}

Output:

30 1

From the lesson: Smart pointers