Object-Oriented Programming in C++

// PL8/abstract.cpp
// The use of an abstract base class
// Niels Walet, last updated 06/01/2022
#include<iostream>
class particle
{
public:
  virtual ~particle(){} // Need this!
  virtual void info()=0; // pure virtual function   
};
class electron : public particle
{
private:
  int charge;
public:
  electron() : charge{-1} {}
  ~electron() {std::cout<<"Electron destructor called"<<std::endl;}
  void info() {std::cout<<"electron: charge="<<charge<<"e"<<std::endl;}  
};
class ion : public particle
{
private:
  int charge,atomic_number;
public:
  // Note constructor short-hand!
  ion(int q, int Z) : charge{q},atomic_number{Z} {}
  ~ion() {std::cout<<"Ion destructor called"<<std::endl;}
  void info() {std::cout<<"ion: charge="<<charge
		       <<"e, atomic number="<<atomic_number<<std::endl;}
};

int main()
{
  particle *particle_pointer = new ion{1,2};
  particle_pointer->info(); 
  delete particle_pointer;
  //
  particle_pointer = new electron;
  particle_pointer->info();
  delete particle_pointer;
  //
  return 0;
}