8 CPP Interview Questions & How To Answer Them

Computer programmers know multiple coding languages and their functions. One popular coding language is CPP, C plus plus (C++). This object-oriented language can accomplish several tasks and is often required for certain jobs in the computer science field. 

What is CPP?

Before preparing for your interview, develop a clear understanding of what C++ is and how it functions. Danish computer scientist Bjarne Stroustrup developed C++ in the 1980s. C++ was part of the existing C classes and extended their functions [1].

Coders and developers use C++, like Java, Python, or any other programming language, to create and develop applications. You can use it to create games, animation, operating systems, web browsers, and more.

Common interview questions for a CPP role

Here are eight questions that interviewers could ask you in an interview for a role that relies heavily on C++ and effective ways to answer them.

1. Tell me about yourself

What they’re really asking: What makes you a good fit for this position?

The first thing you need to do in a job interview is introduce yourself and briefly describe your educational and professional background. The interviewer likely has some information about you via your CV or resume, but it helps to briefly remind them of your qualifications before the proper interview begins.

Other forms this question might take:

• What is your background in programming?

• What other coding project have you worked on?

• Why are you interested in this job?

2. What are the advantages of C++?

What they’re really asking: How well do you know how to use C++?

An interview for a position as a coder, software designer, or computer programmer focusing solely on C++ will require you to define the benefits of using the specific programming language.

C++ has many benefits, including its compatibility with the preexisting C classes. Additionally, it is object-oriented, meaning that its code can instruct the computer or machine on what to do at any given time. C++ is also easy to learn and one of India’s most in-demand programming languages. 

Other forms this question might take:

• What do you like about C++?

• Tell us about your experience using C++

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

What they’re really asking: Do you know the difference between different programming languages?

Since C++ was developed after C, there are several differences between the two programming languages. Neither is necessarily superior to the other; rather, they both have strengths and weaknesses, and you use them for different functions. 

C++ is object-oriented and useful in various applications, while C is function-driven. It doesn’t support object-oriented programming and is better suited to low-level tasks like device drivers. C++ is an extension of C with more features and keywords than C. 

Other forms this question might take:

• When would you use C++ instead of C?

• Are C and C++ the same?

4. What is a class?

What they’re really asking: Do you know how to perform class functions?

In C++, a class is the starting point of the object-oriented function. It is the spot to build off of and the overall grouping of the object. Beneath the class are data members and data functions, which are more specific details and properties about the function of the class that each different class will share. 

A specific example of what a class looks like in object-oriented programming is a good way to answer this question. For example, a class could be books. Different classes could exist for each book or genre, but each book shares data members and data functions, such as words, pages, and a cover. 

Other forms this question might take:

• Give me an example of class.

• What is the importance of class in C++?

5. Tell me the difference between a reference and a pointer

What they’re really asking: How are references and pointers important in C++?

Pointers are a variable that you must dereference to access the value. You can perform arithmetic operations on them. You can’t perform those operations on references, but you can use them by name instead of dereferencing them as you must with pointers. 

You don’t need to initialise a pointer, but you do need to initialise a reference. Additionally, a pointer can have a Null value, and a reference cannot. The most important difference is that you can reassign a pointer to another variable, while you can’t reassign a reference. 

Other forms this question might take:

• What is a reference?

• What is a pointer?

6. Explain Object-Oriented Programming (OOP)

What they’re really asking: Do you know how to use OOP?

C++ is object-oriented programming, so your answer should be similar to what you’d say if the interviewer were to ask you to describe C++ as a programming language.

An object-oriented program does just as it says and focuses on the collection of objects. Each object is part of a much bigger structure containing functions and data. 

Other forms this question might take:

• What is your experience with OOP?

• Which programming languages are you familiar with?

7. What is inheritance?

What they’re really asking: Do you know how inheritance works within C++?

Inheritance is the acknowledgement of shared properties within a class. Using the previous example of the class as books, think of inheritance like this: a science fiction novel and a fantasy novel derive from the same original class. The shared properties of both being books and having pages are an example of inheritance, which connects the two types of books despite their different genres.

Other forms this question might take:

• How are inheritance and class connected?

• Give me an example of inheritance.

8. What is a virtual function?

What they’re really asking: How is a virtual function used in C++?

In C++, virtual functions are member functions in base classes that get redefined after deriving from their base class. You might also refer to it as overriding the base class.

Regardless of whether a pointer or a reference indicates a different object, it must refer back to what the object is in a process called “virtual functions.” The virtual function overrides the base class, and make sure you use the correct object. 

Other forms this question might take:

• What is an example of a virtual function?

• What is the importance of a virtual function?

Prepare for your interview

Your goal is to receive a job offer. First, you must prepare ahead of time for the interview. Using several strategies, you can get ahead before the interview begins.

Research the company

Before the interview, look into the history of the company you’re visiting and decide why you want to work there. The reasons could be that you like the work environment, the type of work they do, or feel aligned with their values. Knowledge of the company and projects they have worked on will give you an idea of your role and answer any questions the interviewer may have about why you chose this company.

Research the role

It’s beneficial to know the exact qualifications and expectations of the role you applied for before the interview. If you’re unsure of anything, ask during the interview. Your potential employer will want you to have all the information necessary to succeed, and you can start by thoroughly researching the job's responsibilities.

Rehearse your interview

Now that you have potential interview questions, consider practising them out loud with friends or colleagues. Doing a rehearsal interview allows you to study anything you’re unsure about and practice speaking to another person.

Next steps

For more information on programming and furthering your knowledge in C++, look to Coursera’s programmes from accredited colleges and universities. Consider exploring Coding for Everyone: C and C++ from the University of California or Object-Oriented Data Structures in C++ offered by the University of Illinois. Try Successful Interviewing from the University of Maryland to enhance your interviewing skills and preparation.