Top C Plus Plus (C++) Interview Questions and Answers

Here are top C++ interview questions,

1. What is C++ (C Plus Plus) or cpp?

C++ is a general-purpose programming language that is an extension of the C programming language. It supports object-oriented programming (OOP) and provides features like classes, objects, and inheritance.

 

2. What is the difference between C and C++?

C++ is an extension of the C programming language, adding features like classes, objects, and inheritance, which make it an object-oriented programming language. C, on the other hand, is a procedural programming language.

 

3. What is an object in C++?

An object is an instance of a class. It represents a real-world entity that has properties (data members) and behaviors (member functions).

 

4. What is a class in C++?

A class is a user-defined data type that encapsulates data members (variables) and member functions (methods) within a single unit.

 

5. What is the difference between a class and an object?

A class is a blueprint or template for creating objects, while an object is an instance of a class.

 

6. What is inheritance in C++?

Inheritance is a feature of object-oriented programming that allows a class to inherit properties and behaviors from another class. It promotes code reusability and helps create a hierarchical class structure.

 

7. What is polymorphism in C++?

Polymorphism is the ability of an object to take on many forms. In C++, polymorphism is achieved through function overloading and virtual functions.

 

8. What is function overloading?

Function overloading is a feature in C++ that allows multiple functions with the same name but different parameters. The compiler determines the correct function to call based on the number, type, and order of the arguments.

 

9. What is a constructor?

A constructor is a special member function of a class that is automatically called when an object of the class is created. It is used to initialize the data members of the object.

 

10. What is a destructor?

A destructor is a special member function of a class that is automatically called when an object goes out of scope or is explicitly destroyed. It is used to clean up resources allocated by the object.

 

11. What is the difference between a shallow copy and a deep copy?

A shallow copy copies the address of the data, so both the original object and the copied object point to the same memory location. A deep copy, on the other hand, creates a new copy of the data, so the original and copied objects have their own separate memory locations.

 

12. What is the difference between a reference and a pointer?

A reference is an alias or nickname for an existing variable, while a pointer is a variable that stores the memory address of another variable.

 

13. What is the 'this' pointer?

The 'this' pointer is a pointer that points to the object itself. It is used inside a member function of a class to refer to the object on which the function is called.

 

14. What is the difference between the 'new' operator and the 'malloc' function?

The 'new' operator is used to dynamically allocate memory for an object and also calls the constructor, while the 'malloc' function is used to allocate memory but does not call the constructor.

 

15. What is the difference between 'delete' and 'delete[]'?

'delete' is used to deallocate memory allocated using 'new', while 'delete[]' is used to deallocate memory allocated using 'new[]'. The latter is used for arrays.

 

16. What are virtual functions?

Virtual functions are member functions that are declared in a base class and overridden in a derived class. They allow the correct function to be called based on the type of the object rather than the type of the pointer or reference.

 

17. What is the difference between public, private, and protected access specifiers?

These access specifiers determine the visibility of class members. 'public' members are accessible from anywhere, 'private' members are only accessible within the class, and 'protected' members are accessible within the class and its derived classes.

 

18. What is an abstract class?

An abstract class is a class that cannot be instantiated and is meant to be subclassed. It can have pure virtual functions, making it an interface for derived classes.

 

19. What are templates in C++?

Templates allow generic programming in C++. They enable the creation of functions and classes that can operate with different types without explicitly specifying the type.

 

20. What is an STL?

STL stands for Standard Template Library. It is a library in C++ that provides generic classes and functions for common data structures and algorithms, such as vectors, lists, queues, sorting, and searching.

Above are few top C++ interview questions. Remember to prepare and expand on these answers.

Good luck with your interview!  👍