OOdesign

Question 1

What is OOP

Answer 1

Object Oriented Programming; Programs are considered as a collection of objects. Each object is nothing but an instance of a class

Question 2

What are the basic concepts of OOP

Answer 2

Abstraction, Encapsulation, Inheritance, Polymorphism

Question 3

What is a class

Answer 3

A class is a representation of a type of object; it is the blueprint that describes the details of an objet

Question 4

What is an object

Answer 4

An object is an instance of a class; it has its own state, behavior and identity

Question 5

Encapsulation

Answer 5

Encapsulation is an attribute of an object, and it contains all data which is hiddent. The hidden data can be restricted to the members of that class

Question 6

Polymorphism

Answer 6

Polymorphism is nothing but assigning behavior or value in a subclass to something that was already declared in the main class. Simply, polymorphism takes more than one form.

Question 7

Inheritance

Answer 7

Inheritance is a concept where one class shares the structure and behavior defined in another class. Ifinheritance applied on one class is called Single Inheritance, and if it depends on multiple classes, then it is called multiple Inheritance.

Question 8

Constructor

Answer 8

Constructor is a method used to initialize the state of an object, and it gets invoked at the time of object creation

Question 9

Function Overloading

Answer 9

Function overloading is defined as a normal function, but it has the ability to perform different tasks. It allows the creation of several methods with the same name which differ from each other by the type of input and output of the function.

Question 10

Abstract Class

Answer 10

An abstract class is a class which cannot be instantiated. Creation of an object is not possible with an abstract class, but it can be inherited. An abstract class can contain only Abstract method. Java allows only abstract method in abstract class while for other languagesit allows non-abstract method as well

Question 11

Call by value

Answer 11

Value passed will get modified only inside the function, and it returns the same value whatever it is passed it into the function

Question 12

Call by reference

Answer 12

Value passed will get modified in both inside and outside the functions and it returns the same or different value

Question 13

Method Overridding

Answer 13

Method overriding is a feature that allows sub class to provide implementation of a method that is already defined in the main class. This will overrides the implementation in the superclass by providing the same method name, same parameter and same return type.

Question 14

Interface

Answer 14

An interface is a collection of abstract method. If the class implements an inheritance, and then thereby inherits all the abstract methods of an interface

Question 15

Difference between overloading and overridding

Answer 15

Overloading is static binding whereas Overriding is dynamic binding. Overloading is nothing but the same method with different arguments , and it may or may not return the same value in the same class itself. Overriding is the same method names with same arguments and return types associates with the class and its child class.

Question 16

Difference between a class and an object

Answer 16

An object is an instance of a class. Objects hold any information , but classes don’t have any information. Definition of properties and functions can be done at class and can be used by the object

Question 17

Abstraction

Answer 17

Abstraction is a good feature of OOPS , and it shows only the necessary details to the client of an object. Means, it shows only necessary details for an object, not the inner details of an object. Example – When you want to switch On television, it not necessary to show all the functions of TV. Whatever is required to switch on TV will be showed by using abstract class

Question 18

Access Modifiers

Answer 18

Access modifiers determine the scope of the method or variables that can be accessed from other various objects or classes

Question 19

Access Modifiers (types)

Answer 19

Private, Protected, Public, Friend, Protected Friend

Question 20

How to call base method without creating an instance

Answer 20

Static method Use Base Keyword from derived class

Question 21

This

Answer 21

THIS pointer refers to the current object of a class. THIS keyword is used as a pointer which differentiates between the current object with the global object. Basically, it refers to the current object

Question 22

Pure virtual function

Answer 22

A pure virtual function is a function which can be overridden in the derived classbut cannot be defined. A virtual function can be declared as Pure by using the operator =0.

Question 23

Virtual

Answer 23

The method can be overridden

Question 24

Can an instance of an abstract class be created?

Answer 24

No

Question 25

Which OOP concept is used as a reuse mechanism

Answer 25

Inheritance is the OOPS concept that can be used as reuse mechanism

Question 26

Exposes only the necessary information

Answer 26

Encapsulation