Abstraction

Abstraction

Abstraction hides implementation details and exposes only essential features. In C++, use abstract base classes containing at least one pure virtual function.

Pure Virtual Functions

A pure virtual function has no body and is declared with = 0. Any class with a pure virtual function becomes abstract and cannot be instantiated directly. Derived classes must override all pure virtual functions to become concrete.

#include <iostream>
using namespace std;

class Instrument {
public:
  virtual void play() = 0;
};

class Guitar : public Instrument {
public:
  void play() override {
    cout << "Strumming guitar\n";
  }
};

class Piano : public Instrument {
public:
  void play() override {
    cout << "Playing piano\n";
  }
};

int main() {
  Instrument* inst1 = new Guitar();
  Instrument* inst2 = new Piano();
  inst1->play();
  inst2->play();
  delete inst1;
  delete inst2;
  return 0;
}