Using std::optional with pointers

Yes, std::optional can be used with pointers. This is particularly useful when you want to express that a pointer might be null, without the risk of null pointer dereferences.

Here's an example of how you might use std::optional with a pointer:

1#include <iostream>
2#include <optional>
3
4class Player {
5 public:
6  Player(const std::string& name) : name(name) {}
7  std::string name;
8};
9
10int main() {
11  std::optional<Player*> player;
12
13  // Player does not exist yet, player is nullopt
14  if (!player) {
15    std::cout << "Player does not exist\n";
16  }
17
18  // Create an object and assign it to player
19  Player real_player("Hero");
20  player = &real_player;
21
22  // Player exists, we can access it
23  if (player) {
24    std::cout << "Player name: "
25      << (*player)->name << '\n';
26  }
27
28  // Reset player to nullopt
29  player = std::nullopt;
30
31  // Player does not exist anymore
32  if (!player) {
33    std::cout << "Player does not exist\n";
34  }
35}

This will output:

1Player does not exist
2Player name: Hero
3Player does not exist

When using std::optional with pointers, you need to be careful about the lifetime of the pointed-to object. In the example above, real_player must outlive player, otherwise player will be left pointing to an object that no longer exists.

Also, when accessing the pointer in an std::optional, you need to first dereference the optional (using *) and then dereference the pointer (using -> or *).

Using std::optional with pointers can help make your code more expressive and safer by explicitly representing the possibility of a null pointer.