Protected Access

#include <iostream>
using namespace std;

class BaseDevice {
protected:
    int id;   // protected int id
};

class DerivedDevice : public BaseDevice {
public:
    void setId(int value) {
        id = value;   // access allowed because id is protected
    }

    void printId() {
        cout << "Device ID: " << id << endl;
    }
};

int main() {
   DerivedDevice d;
   d.setId(101);
   d.printId();
   return 0;
}