C++ Protected Class Members

We have previously seen how we can (and should) make some of the variables and functions of our class private, to prevent code from outside of our class accessing them.

1class Character {
2private:
3  int Health { 100 };
4};
5

The following code will not compile, as private members cannot be accessed from outside the Character class:

1class Monster : public Character {
2public:
3  int GetHealth() { return Health; }
4};
5

We could make Health public again, but we've already seen why that can be problematic. But equally, child classes are inherently linked to their parent. Locking them out from accessing large parts of the parent class can be quite restrictive.

Fortunately, we do have an access level between public and private that solves this problem. This access level is called protected.

protected members cannot be accessed by functions that exist outside our class hierarchy, but they can still be accessed by child classes. This is exactly what we need to solve our problem:

1class Character {
2protected:
3  int Health { 100 };
4};
5
6class Monster : public Character {
7public:
8  void GetHealth() { return Health; }
9};
10

To summarise:

• private members are only accessible within that same class
• protected members are accessible within that same class, and any sub class
• public members are accessible to any code