Top 30 C++ Interview Questions and Answers

Hello, are you acquainted with the knowledge and skills of C++ language???? Planning to design your career in this stream???? Then definitely you might be preparing for a job emphasizing C++ language. Worried about job interview questions??? Don’t get stressed……. this blog helps to familiarize you with the top 30 C++ interview questions and answers asked during technical interviews.  

All about C++ 

C++ is the world’s most popularly used object-oriented programming (OOP) language. It is an extension of the C programming language and gives a clear structure to programs that allow the development of multiple applications used by various platforms.

C++  is quite easy and fun to learn. Moreover, most educational institutions offer C++ courses at graduation and post-graduation degrees. Additionally many private institutions and coaching centers provide C++ courses to technical aspirants. This course comprehends C++ language fundamentals, C++ syntax, complex numbers, friend functions, programming language, header files, C++ pointers, C++ mechanics, C++ exceptions, creating applications, file processing, data structures, coding, allocation of memory and memory management.  

Below is the overview of C++ course.

In addition to the course curriculum, have a glance at the list of a few educational institutions offering C++ courses online.

Henry Harvin

Amongst 500 global Edtech companies, Henry Harvin is one of the leading E-learning platforms offering more than 200 courses in various streams. It is equipped with expert trainers and trained nearly 300,000+ students. This institution has a customer base across 97+ countries and has received the “Best Corporate Training Platform” awardee. It has collaborated with most multinational companies like HCL, HP, IBM, Wipro, Tech Mahindra etc.

C++ Course:

Henry Harvin proffers C++ course online with DS and Algo combo certification course. This course curriculum includes programming concepts, data structures, algorithms, operator overloading, constructors, destructors, classes and objects. This course is affiliated with the American Associate of EFL, Project Management Institute (PMI) and UKcert.

Why Henry Harvin?

• Provides 9-in-1 course with live interactive online classes and brush-up sessions for 1-year
• Issues hallmark certificate based on online examination after course completion
• Get 1-year gold membership and avail the benefits offered by HH
• Access to course content, recorded videos, projects and case studies
• Participate in ongoing internships, hackathons and Bootcamp sessions
• 100% job assistance and placement after the training program
• Get placed in reputed MNCs like Amazon, Microsoft, Google etc

Learning Outcomes:

• Finally, by the end of this course, you will understand the core fundamentals of data structures and algorithms, analyze and implement data structures using C and C++
• Acquire knowledge on memory allocation and memory organization, design efficient algorithms and goal-oriented business techniques

Other Courses:

Apart from C++ course Henry Harvin offers abundant courses like

1. Java foundation with DS and Algo Combo Course
2. SQL Developer Course
3. Python Development Course
4. Software Testing Course

Besides Henry Harvin, the educational companies that provide C++ courses online are as follows.

1. Coursera
2. Udemy
3. Codeacademy
4. Codingninjas

5. Vector Institution
6. Shiksha
7. Besant Technologies
8. C++ Institute
9. Koeing Solutions

Practice practice practice …….. Practice makes a man perfect. Preparation always makes you feel calm, controlled and confident. Below listed are a few C++ interview questions and answers that can be expected in C++ course in a job interview.

Ice-breaking C++ Interview Questions and Answers:

Q1) Tell me about yourself?

A. (Interviewer might have already gone through your resume, but still he/she wants to know more about you.)

Try to be genuine and focus more on your educational qualification, work experience (if any) and achievements.

Q2) What are your strengths and weaknesses?

A. (Here the interviewer wants you to open up and list a few strengths and weaknesses.)

Be honest, instead of revealing your weak areas focus more on your strengths and elaborate on them.

Q3) How did you come to know about this job?

A. (The interviewer is curious to know the source.)

Tell the interviewer how you came across this job. Is it through social media (or) career websites (or)  job portals (or) recommended by any of your friends or colleagues?

Q4) What do you know about this company?

A. (You may expect this question at most company interviews like amazon, google etc. The interviewer expects you to have basic knowledge of that company.)

If possible, research the company’s history, mission, vision, achievements and current issues. Instead of speaking about negative aspects try to speak positively about the company.

Q5) Why should we hire you?

A. (This is quite a challenging question. Here the interviewer wants to check your confidence levels and skill set that aids company growth.)

Answer this question with confidence and mention your skills, strengths and abilities that benefit the company to reach its goals.

Basic level C++ Interview Questions and Answers:

Q6) Can you elaborate on the difference between C and C++?

A. (Here the interviewer wants to check your basic knowledge of these programming languages.)

List out 5 to 6 differences like their functionalities, pointers, constructors, deconstructors, overloading, code structures, data types and keywords etc.

Q7) What are vectors?

A. (Through this question the interviewer wants to check your comprehensive knowledge of data structures, arrays and vectors.)

Vector belongs to the template class in Standard Template Library (STL). These sequence containers can store elements and manage data storage automatically. Vectors are very efficient when compared to dynamic sequence containers. You can either add (or) remove elements at any point in time. Below given is the commonly used syntax:

Type: It defines a data type stored in a vector. For example <int>, <double>, <string>

Variable: It is the name that you select for the data.

Elements: It specifies the number of elements for the data.

It is imperative to direct the type and variable name. Moreover, the number of elements is optional.

Q8) Define class and object in C++.

A. (Here the interviewer wants to check your basic knowledge of this programming language.)

Elaborate on class and object

Class: A class is a user-defined data structure, which works like a blueprint for creating objects in programs. It is considered a building block of programming language. Imagine that a class is a prototype of a house. It comprises all the details like floors, doors, windows etc. In the same way, the class consists of data and functions also known as data members and member functions. 

Object: Objects are real-world entities that have some kind of data and functionality. A class is usually made up of related objects together. We can create objects of a class in any function of a program and yet times we can create objects in a class within the class itself or any other class.

Q9) List the three types of access specifiers in C++.

A. (Here the interviewer wants to check your basic knowledge of this programming language.)

Access specifiers explain how the attributes and methods of a class can be accessed. There are three types of access specifiers which are as follows: 

Q10) Explain how constructors and deconstructors work together in C++.

A. (Through this question the interviewer wants to check your understanding of constructors, deconstructors and their correlation.)

A constructor is a special function that is called by the compiler to assign a value to the new object within the class. It is named similar to class and can either be defined within the class (or) outside the class yet times. There can be more than one constructor in one class as they have different parameters.

A deconstructor exhibits the opposite work of a constructor. whenever an object is deleted the deconstructor destroys the object and unallocated its memory.

Intermediate level C++ Interview Questions and Answers:

Q11) What are the different types of variables in C++?

A. (At this level the interviewer poses some technical questions and expects you to be strong in core areas.)

Variable types regulate the size and layout of variable memory. Some of the variable types in C++ are as follows:

Q12) Can you elaborate on function overloading and overriding?

A. (At this level the interviewer poses some technical questions and expects you to be strong in core areas.)

Function overloading is a process in which two or more functions are given the same names but different parameters. This is a type of polymorphism. The objective of function overloading is to improve readability and memory optimization.

Whereas, function overriding is a procedure in which the derived class is given the same function similar to the base class. This is a type of compile-time polymorphism. The aim of function overriding is to improve code reusability and save memory.

Q13) Explain the function of the “auto” keyword in C++.

A. (Here the interviewer tests your application skills based on your professional experience.)

The auto keyword notifies the compiler to use the expression of a declared variable automatically. It can be used instead of variable type as it is efficient and strong.

Q14) According to you what are the drawbacks of C++?

A. (Here the interviewer tests your practical skills based on your professional experience.)

Try to be genuine and list a few problems/drawbacks you have experienced while working on this programming language.

1. The pointers and variables cause security threats
2. As memory allocation is done manually, it consumes more time
3. It does not support garbage pickup, build-in code threats and dynamic memory allocation
4. It is complex, less flexible and requires a lot of money for maintenance

Q15) How can you optimize a C++ program?

A. (Here the interviewer tests your practical skills based on your professional experience.)

List some strategies you have applied while executing C++ programs.

Q16) Mention the types of various preprocessor directives in C++.

A. (At this level the interviewer poses some technical questions and expects you to be strong in core areas.)

Preprocessor directives assist the compiler on how to process the information before compilation starts. The three most commonly used preprocessor directives are as follows:

Q17) How is multithreading conducted in C++?

A. (Here the interviewer tests your practical skills based on your professional experience.)

While creating a new thread, the user must use the syntax “#include<thread>” header to give access to the “std::thread” object. After this, a call-back mechanism has to be attached to the original thread to create a new one. 

Q18) Discuss the difference between shallow copy and deep copy.

A. (Here the interviewer tests your practical skills based on your professional experience.)

Shallow copy stores the reference of the objects to its original memory address and whereas the deep copy creates a new and separate copy of the object with a unique memory address. Deep copy is relatively slow when compared to shallow copy.

Q19) When should we use multiple inheritance?

A. (Here the interviewer tests your practical skills based on your professional experience.)

You can answer this depending on your work experience. Usually, you can answer this question in three ways.

1. Never
2. Rarely
3. When the problem domain cannot be modeled

Q20) Does C++ support Exception handling?

A. (Here the interviewer tests your theoretical and practical skills based on your professional experience.)

Yes, of course, C++ supports Exception handling. Sometimes the code provided by us can tend to malfunction though it is error-free. This is called an exception. When an exception occurs the compiler has to throw back it so that we can know that an exception has occurred. The compiler has to handle the exception so that the program flow continues smoothly. This is called exception handling.

Advanced level C++ Interview Questions and Answers:

Q21) Name the operators that cannot be overloaded.

A. (Here the interviewer tests your theoretical and practical skills based on your professional experience.)

The operators that cannot be overloaded in C++ are given below.

Q22) Mention the order in which local objects are destructed in C++.

A. (Here the interviewer tests your theoretical and practical skills based on your professional experience.)

Let’s assume that you have created three objects. During the process of creation they are created one after the other, but while deleting them the last will be destroyed first and the first created will be destroyed at the end. Even the same is applied to an array of objects, they will be destructed in the reverse order of creation.

An example is given below:

In this example, c’s destructor is executed first, then b’s destructor and a’s destructor is executed at the end.

Q23) What is the purpose of the Extern Storage Specifier?

A. (Here the interviewer tests your theoretical and practical skills based on your professional experience.)

The Extern Storage Specifier allows you to mention the objects where various source files can make use of them.

In the above code, the value of “i” is visible outside the file.

Q24) Write a function to print 1 2 3.

A. (Here the interviewer tests your theoretical and practical skills based on your professional experience.)

This can be done by using a static variable. Generally, a static variable retains its value across the function calls. They are declared through the keyword “static”.

This function prints 1 2 3 if it is called thrice.

Q25) Which storage classes are supported by C++?

A. (Here the interviewer tests your theoretical and practical skills based on your professional experience.)

C++ supports the following storage classes:

Automatic, External, Static, Register and Mutable.

Q26) What is the difference between delete and delete []?

A. (Here the interviewer tests your theoretical and practical skills based on your professional experience.)

General questions in  C++ Interview Questions and Answers:

Q27) If you have to lead a team. What do you have to say about your leadership skills?

A. (Here the interviewer wants to check on your abilities and skills.)

Think well before answering, you have to address your leadership skills and team requirements, goals etc. Both of these aspects need to be given equal importance. 

Q28) What is your current CTC? In case we recruit you, what are your salary expectations?

A. Be genuine while answering this question. Mention your previous salary along with the benefits provided by the organization. Correlating to that put forward your salary expectations by including your achievements, work style and capabilities. 

Q29) If you have any questions, we would like to answer them?

A. If you have any doubts or concerns, put them forward so that they can be addressed.

Q30) How soon can you join once we confirm your position?

A. Confirm the date of joining and you can also mention the relieving date in your previous company.

Conclusion:

Preparation plays a key role for any job interview. Try to note down the important points, have good communication skills and be confident. If required attend a few mock interview sessions which help you to overcome anxiety. I hope this article helps you to get acquainted with C++ interview questions and answers at all levels and ace the job.

Frequently asked questions: