.NET Tutorials, Forums, Interview Questions And Answers
Welcome :Guest
 
Sign In
Register
 
Win Surprise Gifts!!!
Congratulations!!!


Top 5 Contributors of the Month
david stephan

Home >> Interview Question >> .NET Framework >> Post New Question Subscribe to Interview Questions

What are constructors and destructors

Posted By :Ashutosh Jha     Posted Date :May 23, 2014    Points :40   Category :.NET Framework 
Constructors and destructors are special methods.

Constructors and destructors are special methods of every class.

Each class has its own constructor and destructor and are called automatically when the instance of a class is created or destroyed.

The constructor initializes all class members whenever you access the class and the destructor destroys them when the objects are not required anymore.

You can also find related Interview Question to What are constructors and destructors  below: 

I thought destructors didn't exist in C#.Why can I declare one?

  
You can declare a method that looks like a C++ destructor such as ~Employee(). But it really becomes a shorthand way to define System.Object.Finalize.The Finalize method is not the same as a C++ destructor.A short explanation is that C++ destructors are called when the call stack unwinds.The Finalize method will be called when the garbage collector of the CLR is ready to destroy the object. (More...)

This is the progam using inheritence, what is the order of calling constructors and what is the output?
Public Class ConstructorEx
Public Class Class1
Dim a As Integer
Sub New()
a = 1
Console.WriteLine("a in initialized in Class1")
End Sub
End Class

Public Class Class2
Inherits Class1
Dim b As Integer
Sub New()
b = 1
Console.WriteLine("b in initialized in Class2")
End Sub
End Class
Public Class Class3
Inherits Class2
Dim c As Integer
Sub New()
c = 1
Console.WriteLine("c in initialized in Class2")
End Sub
End Class

Shared Sub main()
'Creation of the object of type Class3
Dim c As New Class3()
Console.ReadLine()
End Sub
End Class

  
In this example creation of the object of type class3 calls the Class3 constructor and that constructor calls Class2 Constructor Class2 Calls Class1 Constructor.So first Class1 constructor will execute and then control will be trasfered to class2 constructor,After executing the class2 constructor the control will be treansfered to Class3 constructor.
means

Class1
|---->Sub New()---------------------|
| 'First it will execute <-----|
| End Sub |
| |
| Class2 |
|--->Sub New()----------------------|
| 'Second it will execute<-------|
| End Sub |
| |
| Class3 |
----Sub New()-----------------------|
'Third this will executes<-----|
End Sub

Means In the Creation of the object of type C, First Class1 Constuctor initializes the data, then class2 then class3.

So output of this program is
a in initialized in Class1
b in initialized in Class2
c in initialized in Class3
(More...)

What are the various types of constructors?

  


There are three various types of constructors , and they are as follows:.

- Default Constructor - With no parameters.

- Parametric Constructor - With Parameters. Create a new instance of a class and also passing arguments simultaneously.

- Copy Constructor - Which creates a new object as a copy of an existing object.

(More...)

What is destructors in C#?

  
Destructor is called for a class object when that object passes out of scope or is explicitly deleted.A destructors as the name implies is used to destroy the objects that have been created by a constructors.Like a constructor , the destructor is a member function whose name is the same as the class name but is precided by a tilde.
(More...)

What is the concept of destructors in VB.NET?

  
Destructors are used to de-allocate resources i.e. to clean up after an object is no longer available. (More...)

Quick Links For Interview Questions Categories:
ASP.Net Windows Application   .NET Framework   C#   VB.Net   ADO.Net  
Sql Server   SharePoint   Silverlight   OOPs   JQuery   JavaScript/VBScript
Biztalk Patten/Practices .IIS WCF WPF WWF
Networking Aptitude Others   All      

Find questions, FAQ's and their answers related to .NET, C#, Vb.Net, Sql Server and many more.

 
Now you can find lots of .NET, C#, Vb.Net, SQL Server,Windows, ASP.Net related Questions and their Answers here at www.dotnetspark.com. Our aim is to help you pass your certification Exams (MCP, MCSD, MCAD etc.,) with flying scores and get good name in your company.

So, Start looking our Interview Question section daily and improve your .NET Skills. You can also help others by posting Interview Questions and their Answers in this section.


Hall of Fame    Twitter   Terms of Service    Privacy Policy    Contact Us    Archives   Tell A Friend