Polymorphism with virtual and override

Polymorphism with virtual and override.cs

using System;

/* Polymorphism with virtual and override
 * 
 * Base class reference variables can point to a child class object
 * 
 * !@!@ Polymorphism enables us to invoke derived class methods using a base class reference variable at RUN-TIME !@!@
 */

public class Employee
{
    public string FirstName = "Derrik";
    public string LastName = "Nasca";

    public virtual void PrintFullName() //indicates to the derived classes that it can override this virtual method if they choose to do so
    {
        Console.WriteLine(FirstName + " " + LastName);
    }
}

public class FullTimeEmployee : Employee
{
    public override void PrintFullName()
    {
        Console.WriteLine(FirstName + " " + LastName + " - Full Time");
    }
}

public class PartTimeEmployee : Employee
{
    public override void PrintFullName()
    {
        Console.WriteLine(FirstName + " " + LastName + " - Part Time");
    }
}

public class TemporaryEmployee : Employee
{
    public override void PrintFullName()
    {
        Console.WriteLine(FirstName + " " + LastName + " - Temporary");
    }
}

public class Program
{
    public static void Main()
    {
        var employees = new Employee[4]; //create an array with 4 employee objects

        //assign a child class object to a base class reference variable. each element of the array will be assigned a different type of employee object
        employees[0] = new Employee();
        employees[1] = new FullTimeEmployee();
        employees[2] = new PartTimeEmployee();
        employees[3] = new TemporaryEmployee();

        foreach (Employee e in employees) //for each employee object in the employees array
        {
            
            e.PrintFullName();  //this will invoke the overriden PrintFullName method from each class during run-time

        }

    Console.ReadKey();
    }
}