OOPS

-

class A
    {
        public void Display()
        {
            Console.WriteLine("class A display");
        }
    }

    class B : A
    {
        public void Display()
        {
            Console.WriteLine("class B display");
        }
        public void Print()
        {
            Console.WriteLine("class B print");
        }
    }

    class Program
    {

        static void Main(string[] args)
        {
            A obj = new B();
            obj.Display();  // will call method of class A. why?

            Console.ReadLine();
        }

    }


OutPut :  class A display


Explanation:
When we extend class A into class B, it will inherit all its methods and properties. So, in this case, obj is the instance variable of class A
but containing the newly created object of class B. So what happens is, after executing the line, obj now contains the methods of both classes i.e, class A as well as class B. but, when we call any method only class A methods will be called because reference of class A only is saved in obj.

Comments

  1. Anonymous27 February 2017 at 02:55

    If we override the Class B's method then it will get executed B's Method

    ReplyDelete

Post a Comment

Popular posts from this blog

iframe vs embed vs object in HTML 5

-
HTML5 - Embedded content <iframe> vs <embed> vs <object> Embed, object and iframe tags are used to embed external resources in html document. <iframe> Primarily used to include resources from other domains or subdomains but can be used to include content from the same domain as well.   < iframe   id = "myFrame"   frameborder = "0"   allowtransparency = "true"   src = "report.html"   width = "100%"   height = "700" style = "border:none;" >   </ iframe >  Pros : ·          The  <iframe> 's strength is that the embedded code is 'live' and can communicate with the parent document. Cons : ·          Iframes Bring Security Risks: o    A malicious user can run a plug-in, change the source site URL, hijack your users' clicks ·       ...
Read more

Constructor in c#

-
Question: W hat is the output of the below code?  namespace ConsoleApplication1 {     class A     {         public A()         {             Console .WriteLine( "A.Constructor" );         }         public A( string abc)         {             Console .WriteLine( "A.Constructor " + abc);         }         public void Show()         {             Console .WriteLine( "A.Show()" );         }     }     class B ...
Read more

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 * Basic...
Read more