As I said, unique_ptr (or any of the others), do not check for null. So you can do this, and it will cause a segfault: std::unique_ptr<int> a; printf("

As I said, unique_ptr (or any of the others), do not check for null. So you can do this, and it will cause a segfault: std::unique_ptr<int> a; printf("%d\n", *a); Similarly unique_ptr::operator[] doesn't (and can't) do bounds checking, for example: std::unique_ptr<int[]> a = std::make_unique<int[]>(2); printf("%d\n", a[2]); There's also no attempt to limit the construction of invalid smart pointers, for example: int num; std::unique_ptr<int> a(&num); Smart pointers simplify memory management, and they're slightly harder to misuse than regular pointers, but they simply make no attempt at providing memory safety.