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In which order the constructor is called for an inherited class?

Posted By :Jean Paul     Posted Date :December 16, 2010    Points :15   Category :.NET Framework 
Constructor of Parent class is called

Then,

Constructor of Child class

You can also find related Interview Question to In which order the constructor is called for an inherited class?  below: 

What is Private Constructor? and it's use? Can you create instance of a class which has Private Constructor?

  
When a class declares only private instance constructors, it is not possible for classes outside the program to derive from the class or to directly create instances of it. (Except Nested classes)
Make a constructor private if:

1) You want it to be available only to the class itself. For example, you might have a special constructor used only in the implementation of your class' Clone method.

2) You do not want instances of your component to be created. For example, you may have a class containing nothing but Shared utility functions, and no instance data. Creating instances of the class would waste memory. (More...)

Are private class-level variables inherited?

  
Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited. But they are. (More...)

Are private class-level variables inherited?

  
Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited. But they are. (More...)

Can you allow class to be inherited, but prevent the method from being over-ridden?

  
Yes, just leave the class public and make the method sealed. (More...)

Whether we can create a private constructor for a class?

  
Yes it is possible. we can create a private constructor for a class (More...)

How to block a class from being inherited further?

  
Use sealed keyword.

Eg: public sealed class TheClass
{
} (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...)

Are private class-level variables inherited?

  
Yes,private class members are inheritable, but they are not accessible (More...)

How Many Constructor we can create in side the class.

  
we can create more constructor inside the class (More...)

In WCF, suppose you have a derived class inherited from a datacontract class, will the derived class automatically have a datacontract as well ?

  
The Data contract is not inherited, so any derived class, would have to be explicitly declared as having a Data contract attribute as well.

(More...)

What is the difference between a Struct and a Class?

  
The struct type is suitable for representing lightweight objects such as Point, Rectangle, and Color. Although it is possible to represent a point as a class, a struct is more efficient in some scenarios. For example, if you declare an array of 1000 Point objects, you will allocate additional memory for referencing each object. In this case, the struct is less expensive.

When you create a struct object using the new operator, it gets created and the appropriate constructor is called. Unlike classes, structs can be instantiated without using the new operator. If you do not use new, the fields will remain unassigned and the object cannot be used until all of the fields are initialized.

It is an error to declare a default (parameterless) constructor for a struct. A default constructor is always provided to initialize the struct members to their default values.

It is an error to initialize an instance field in a struct.

There is no inheritance for structs as there is for classes. A struct cannot inherit from another struct or class, and it cannot be the base of a class. Structs, however, inherit from the base class Object. A struct can implement interfaces, and it does that exactly as classes do.

A struct is a value type, while a class is a reference type. (More...)

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