Basic OOPs Interview Questions..!
OOPs Definition:
Object-Oriented Programming is basically a programming style that we used to follow in modern programming. It primarily revolves around classes and objects. Object-Oriented programming or OOPs refers to the language that uses the concept of class and object in programming. The popular object-oriented programming languages are c++, java, python, PHP, c#, etc. The main objective of OOPs is to implement real-world entities such as polymorphism, inheritance, encapsulation, abstraction, etc. The main aim of OOP is to bind together the data and the functions that operate on them so that no other part of the code can access this data except that function.
Class A class is a logical entity used to define a new data type. A class is a user-defined type that describes what a particular kind of object will look like. Thus, a class is a template or blueprint for an object. A class contains variables, methods, and constructors. Classes are very useful in programming. Consider the example of where you don't want to use just one car but 100 cars. Rather than describing each one in detail from scratch, you can use the same car class to create 100 objects of the type 'car'. You still have to give each one a name and other properties, but the basic structure of what a car looks like is the same. The car class would allow the programmer to store similar information unique to each car (different models, maybe different colors, etc.) and associate the appropriate information with each car.
Object An object is an instance of a Class. It is an identifiable entity with some characteristics and behavior. To access the members defined inside the class, we need to create the object of that class. Objects are the basic units of object-oriented programming. It may be any real-world object like a person, chair, table, pen, animal, car, etc. Code in object-oriented programming is organized around objects. Once you have your objects, they can interact with each other to make something happen.
What are the benefits of using OOPs?
Answer: OOPs allow for greater clarity in programming, making it easier to solve complicated problems.
Through inheritance, code can be reused, decreasing repetition.
Encapsulation binds data and code together.
Because OOPs enable data hiding, private information is kept hidden.
To make it easier to tackle problems can be broken down into smaller chunks.
Polymorphism allows the program to be more flexible by allowing entities to have numerous forms.
What are the drawbacks of using OOPs?
Answer: Some of the drawbacks of OOPs are:-
Usually, it isn't appropriate for minor issues.
Intensive testing is required.
It takes a longer time to fix the problem.
It requires proper planning.
7. What are the benefits and drawbacks of OOP?
Answer: Below is the some of the advantages and disadvantages of OOPs:-
Advantages of OOP
It follows a bottom-up approach.
It models the real world well.
It makes code reusability possible.
Using abstraction, the user is not exposed to unnecessary data.
OOP requires designers to go through a long and extensive design phase, which yields a better design with fewer faults.
Break down a large problem into smaller chunks.
Programmers are able to achieve their objectives more quickly.
Reduces the amount of complexity.
Code may be easily redesigned and extended without affecting other features.
Disadvantages of OOP
Proper planning is required.
Program design is tricky.
The programmer should be well skilled.
Classes tend to be overly generalized.
What are the differences between class and object?
Answer: Some of the differences between class and object are given below
| Class | Object | | --- | --- | | Class is a logical entity. | Object is a real-world entity. | | Class is conceptual. | Object is real. | | Class binds data and methods together into | Object is just like a variable of a class. | | Class does not occupy space in the memory. | Object occupies space in the memory. | | Class is declared once. | As and when needed, several objects can | | A class can exist without any object. | Objects cannot exist without the class. |
What is the difference between class and structure?
Answer: Some of the differences between class and structure are given below:-
| Class | Structure | | --- | --- | | Class is a group of common object that shares common properties. | The structure is a collection of different data types. | | Its members are private by default. | Its members are public by default. | | The keyword class defines a class. | The keyword struct defines a structure. | | A class instance is referred to as an object. | A structure variable is an instance of a structure. |
What is the definition of inheritance?
Answer: OOPs has a feature called inheritance, which allows classes to inherit common properties from other classes. If a class called vehicle exists, other classes like 'car,' 'bike,' and so on can inherit common characteristics from it. This characteristic assists in the removal of extraneous code, resulting in smaller overall code size.
What are various types of inheritance?
Answer: Various types of inheritance are:-
Single inheritance
Multiple inheritances
Multilevel inheritance
Hierarchical inheritance
Hybrid inheritance
What are the limitations of Inheritance?
Answer: Yes, greater powers bring greater challenges. Inheritance is a great feature in OOPs, but it comes with some drawbacks. Inheritance takes longer to process since it must go through numerous classes in order to be implemented. Inheritance also involves two classes: a base class and a child class, which are extremely closely related. As a result, if changes are required, they may need to be made in both classes. Inheritance may be difficult to implement as well. As a result, if not implemented appropriately, this could result in unexpected errors or inaccurate outputs.
What is the difference between multiple and multilevel inheritance?
Answer: The following are the differences between multiple and multilevel inheritance:-
| Multiple Inheritance | Multilevel Inheritance | | --- | --- | | When a class inherits from more than one base class, multiple inheritance is used. | Multilevel inheritance means a class inherits from another class which itself is a subclass of some other base class. | | Example: A class defining a child inherits from two base classes, Mother and Father. | Example: A class describing a sports car will inherits from a base class Car which in turn inherits another class Vehicle. |
What is method overriding, and how does it work?
Answer: Method overriding is an OOPs feature that allows a child class or subclass to rewrite methods in the base or parent class. The overridden method has the same name as the original, as well as the same signature, which refers to the arguments supplied and the return type.
What are virtual functions?
Answer: Virtual functions are present in the parent class and are overridden by the subclass. These functions are used to achieve runtime polymorphism. They allow a base class to define a method as virtual, indicating that derived classes may override it. When an object of a derived class is accessed through a pointer or reference of the base class, the appropriate overridden function in the derived class is invoked based on the actual object type.
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