What is the need of method overriding ???

When we need to extend the Parents class method's behavior with some modifications.

This is the situation where we inherit the class and override the methods which are required as per our business requirement.

namespace testApp

{

    abstract class Employee

    {

        public int EmployeeID { get; set; }

        public String EmployeeName { get; set; }

        public double BasicSalary { get; set; }

        abstract public void CalculateSalary();

    }

    class PermanentEmployee : Employee

    {

        public override void CalculateSalary()

        {

            double HRA = 20 * BasicSalary / 100;

            double SpecialAllowance = 10 * BasicSalary / 100;

            double total = BasicSalary + HRA + SpecialAllowance;

            Console.WriteLine("Salary of  {0} is :{1}rs.", EmployeeName, total);

        }

    }

    class ContractEmployee : Employee

    {

        public double NoOfHours { get; set; }

        //extend the Parents class method's behaviour  with some modifications.

        public override void CalculateSalary()

        {

            double total = NoOfHours * BasicSalary;

            Console.WriteLine("Salary of  {0} is :  {1}rs.", EmployeeName, total);

        }

    }

    class Program

    {

        static void Main(string[] args)

        {

            PermanentEmployee permanentEmployee = new PermanentEmployee();

            permanentEmployee.EmployeeName = "PermanentEmployee";

            permanentEmployee.BasicSalary = 25000;

            permanentEmployee.CalculateSalary();

            Console.WriteLine();

            ContractEmployee contractEmployee = new ContractEmployee();

            contractEmployee.EmployeeName = "ContractEmployee";

            contractEmployee.BasicSalary = 5000;

            contractEmployee.NoOfHours = 40;

            contractEmployee.CalculateSalary();

            Console.ReadLine();

        }

    }

}