oops concepts in net interview questions and answers | object oriented programming interview questions and answers ~ For Job Seekers

oops concepts in net interview questions and answers , object oriented programming interview questions and answers

Hi today iam sharing some more oops concepts in .net interview questions.

1. How has exception handling changed in the .NET Framework 4.0 Explain?

In .NET 4.0, a new namespace, System.Runtime.ExceptionServices, has been introduced which contains following classes for handling the exceptions .

1) HandleProcessCorruptedStateExceptionsAttribute Class - Enables managed code to handle corrupted state exceptions that occur in an operating system. These exceptions cannot be caught by specifying the try...catch block. To handle such exceptions, you can apply this attribute to the method that is assigned to handle these exceptions.
2)FirstChanceExceptionEventArgs Class - Generates an event whenever a managed exception first occurs in your code, before common language runtime begins searching for event handlers.

2 What is a delegate Explain?

A delegate is similar to a class that is used for storing the reference to a method and invoking that method at runtime, as required. A delegate can hold reference of only those methods whose signatures are same as that of the delegate. Some of examples of delegates are type safe functions, pointers.

3. What is the syntax to inherit from a class in C#?

When a class is derived from another class, then the members of the base class become members of the derived class. The access modifier used while accessing members of the base class specifies access status of the base class members inside the derived class.

The syntax to inherit a class from another class in C# is as follows:
class MyNewClass : MyBaseclass

4. State the features of an interface.

An interface is a template that contains only the signature of methods. The various features of an interface are as follows:

An interface is used to implement multiple inheritance in code. This feature of an interface is quite different from that of abstract classes because a class cannot derive the features of more than one class but can easily implement multiple interfaces.
It defines a specific set of methods and their arguments.
Variables in interface must be declared as public, static, and final while methods must be public and abstract.
A class implementing an interface must implement all of its methods.
An interface can derive from more than one interface whereas abstract cannot.

5 Can you use the 'throws' clause to raise an exception if no justify?

No, the throws clause cannot be used to raise an exception. The throw statement signals the occurrence of an exception during the execution of a program. When the program encounters a throw statement, the method terminates and returns the error to the calling method.

6. Define an array.

An array is defined as a homogeneous collection of elements, stored at contiguous memory locations, which can be referred by the same variable name

7 What are methods?

Methods are the building blocks of a class, in which they are linked together to share and process data to produce the result. In other words, a method is a block of code that contains a series of statements and represents the behavior of a class.

8. What is namespace?

Namespace is considered as a container that contains functionally related group of classes and other types.

9. Do events have return type?

No, events do not have an return type.

10 What is the function of the Try-Catch-Finally block explain?

The try block encloses those statements that can cause exception and catch block handles the exception, if it occurs. Catch block contains the statements that have to be executed, when an exception occurs. The finally block always executes, irrespective of the fact whether or not an exception has occurred. The finally block is generally used to perform the cleanup process. If any exception occurs in the try block, the program control directly transfers to its corresponding catch block and later to the finally block. If no exception occurs inside the try block, then program control transfers directly to the finally block.

11. How can you prevent a class from overriding in C# and Visual Basic?

You can prevent a class from overriding in C# by using the sealed keyword; whereas, NotInheritable keyword is used to prevent a class from overriding in the Visual Basic.

12. What are abstract classes? What are characteristics of an abstract class?

An abstract class is a class that cannot be instantiated and is always used as a base class.
The following are the characteristics of an abstract class: