How Obfuscator works

Explain how Obfuscator works?


Obfuscators protect the source code from being hacked. Encryption and Decryption are processes from where you can get the data back. However these differ from what obfuscation is. In obfuscation, a program become out of the reach of hackers although it functions the same way it is supposed to. Optimizations too get applied to the process of obfuscation in order to make the program fast.



Obfuscator simply renames all types and namespace etc to meaningless code making it non human readable. This diminishes the possibility of reverse engineering. For example


private void AddEmp(Employee employee) 
{
   {
      this.EmpList.Add(employee);
   }
}


It gets converted to following code.


private void a(a b) 
{
    {
      a.a.Add(b);
    }
}

Abstract classes in C#.NET

Define abstract class in C#.NET.


Abstract classes in C#.NET has following features :
Abstract class cannot be instantiated.
Same concept in C++ known as pure virtual method. 
A class that must be inherited and have the methods over-ridden. 
A class without any implementation.

Constructor and Destructor in .NET

What is a Constructor? 


It is the first method that are called on instantiation of a type. It provides way to set default values for data before the object is available for use. Performs other necessary functions before the object is available for use.


What is a Destructor?


It is called just before an object is destroyed. It can be used to run clean-up code. You can't control when a destructor is called since object clean up by common language runtime.

Implement a Web Service in .NET

Explain with code sample how to Implement a Web Service in .NET?

Following is code in VBScript and C# both respectively.

In VBScript :

<%@ WebService Language="VBScript" Class="KmToMConvert" %>

Imports System

Imports System.Web.Services

Public Class KmToMConvert :Inherits WebService

   <WebMethod()> Public Function KilometerToMeter(ByVal Kilometer As String) As String 

         return (Kilometer * 1000)

         end function

end class

In C# :

[WebService(Namespace = http://tempuri.org/)]

[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

[System.ComponentModel.ToolboxItem(false)]

// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 

// [System.Web.Script.Services.ScriptService]

public class Service1 : System.Web.Services.WebService

{

     [WebMethod]

     public string HelloWorld()

     {

            return "Hello World";

     }

}

Private virtual methods in C#.NET

Can private virtual methods be overridden in C#.NET? 


No, moreover, you cannot access private methods in inherited classes, They have to be protected in the base class to allow any sort of access.