Question

I have been programming in C++ for sometime and now I am starting to work with C# but I cannot get the idea of virtual and override keywords. Since the pointers and all related to it’s stuff is mostly gone from C++ we do not really need them do we ? Or I am missing some major points of C# programming.

Example :

namespace ConsoleApplication1
{
    public class Employee
    {
        public virtual void GetPayCheck()
        {
            Console.WriteLine("employee gets his pay check ");
        }

        public void Work()
        {
            Console.WriteLine("employee works ");
        }
    }
    public class Manager : Employee
    {
        public override void GetPayCheck()
        {
            Console.WriteLine("MANAGER gets his pay check ");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Employee emp = new Employee();
            Manager exec = new Manager();
            emp.Work();
            exec.Work();
            emp.GetPayCheck();
            exec.GetPayCheck();
        }
    }
}

Even if I omit virtual or override keywords ( or both ) I still get the same output.
What am I

Answer 1

Using virtual and override allows you to completely replace the Work method, regardless of what type the variable is declared as. If a method is declared as virtual, the CLR checks if the object is a derived class and if the method has been overridden. If a method is not virtual, the CLR just calls the method with the name Work from the type that the object has been declared as.

    static void Main(string[] args)
    {
        Employee emp = new Employee();
        Manager exec = new Manager();

        DoWork(emp); // employee works and gets pay check
        DoWork(exec); // if virtual and override are used, MANAGER get pay check
                      // however, if you don't override the method, DoWork
                      // will treat the argument as an Employee.
    }

    static void DoWork(Employee emp)
    {
        emp.Work();
        emp.GetPayCheck();
    }