Inheritance and virtual functions

Reuse code, and let each class supply its own behaviour.

C++

#include <iostream>
#include <memory>
#include <vector>
using namespace std;

class Staff {
public:
  virtual ~Staff() = default;
  virtual int pay() const = 0;
};

class Developer : public Staff {
public:
  int pay() const override { return 30000; }
};

class Intern : public Staff {
public:
  int pay() const override { return 5000; }
};

int main() {
  vector<unique_ptr<Staff>> team;
  team.push_back(make_unique<Developer>());
  team.push_back(make_unique<Intern>());
  for (const auto &s : team) {
    cout << s->pay() << "\n";
  }
  return 0;
}

Output

30000
5000

virtual picks the right version at run time, and = 0 makes the class abstract. A base class needs a virtual destructor. unique_ptr frees the object automatically, so you do not need new and delete.

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