Most Common C++ Interview Questions & Answers [UPDATED 2023]
Table of content
C++ is still as important now as it was when it first emerged in the mid-1980s. As a general-purpose programming language, the imperative, object-oriented programming language is extensively employed. As a result, a lot of industries need individuals to be competent in C++. If you want to improve your C++ language abilities even further, here are some of the greatest C++ lessons available.
Now, what is C++?
C++ is an object-oriented computer language established as part of the development of the C family of languages by renowned computer scientist Bjorn Stroustrup. The word C++ is pronounced “see-plus-plus.” It was created as a cross-platform enhancement to C to provide developers more control over memory and system resources.
If you’re preparing for a C++ job interview, here are the 15 most common C++ interview questions to help you nail your own C++ interview preparation:
C++ Interview Questions With Answers In 2023
Please Define Encapsulation in C++?
Answer: Encapsulation is the process of connecting a class’s data and functionalities. It is the key to restrict unauthorized access to data for security purposes. This can happen through the use of a class’s functions. For example, only the authorized individual with the appropriate login ID and password may use the customers’ net banking facility. That is also solely for his/her portion of the data in the bank data source.
What is an abstraction in C++?
Answer: An abstraction in C++, is the concealment of internal implementations and the presentation of only the necessary details. For example, when sending an essential message through email, simply writing and hitting the send button is useful. This is just the notification of success that confirms the receipt of your email. But, the procedure used to send the data through email is unrevealed since it is irrelevant to you.
Could you define an access specifier and its various types in C++?
Answer: An access specifier allows you to declare how class members, such as functions and variables, will be accessible outside of the class’s scope. In C++, there are three types of access specifiers:
- Private: Such class members are unavailable outside the physical process and may only be accessible inside the same class. Secret parent class members have access just to children’s courses.
- Protected: the protected members of the parent class can be accessible by the child classes as well as the class in which they are well-known.
- Public: throughout the software, class participants that had designated as the public can be accessible (code).
What is the function of the keyword “Volatile”?
Answer: ‘Volatile’ is a function to declare that the variable concerned is volatile and so tells the compiler to externally alter the variable – so, The reference variable may prevent compiler optimization.
Define storage class in C++? Name some?
answer: Specifically the storage class in C++ is similar to life and even symbols, including variables, features, etc. Some of the names for the C++ storage class are mutable, auto, static, external, register, etc.
Can we have a recursive inline function in C++?
Answer: Although an inline function can come from inside C++, Cannot create the inline code from the compiler. This is because at the time of compilation the compiler will not identify the depth of the recursion. But, if a compiler with a competent optimizer overrides the real depth, it can enter recursive calls until a specific amount of depth has set and non-recursive calls are in place at the building time.
Define an Inline Function in C++? Write its syntax. Is it possible for the C++ compiler to ignore inlining?
Answer: C++ enables inline functions to decrease overhead call functionality. As the name indicates, when called an inline function will extend in line. The complete code is entering or substituted at the specific moment of the call of the inline function once the inline function is invocable. The replacement will be complete at compile time by the C++ compiler. Small inline functions might improve the efficiency of the program.
A typical inline function’s syntax is:
Could you explain ‘this’ pointer?
Answer: The ‘this’ pointer is a constant pointer and contains the current object’s memory location. It passes all non-static function calls as a hidden parameter. It is also possible in all non-status functions as a local variable. The ‘this’ pointer is not available to them since the static member function may be evocative without any object, i.e. with the class name.
What are the differences between C and C++?
- C++ does let references, C does not support references.
- C++ is inherent in features like amic functions, overload function, legacy, templates, and virtual functions. The C programming language is not accessible.
- Usually, we use C the conventional If-else approach as an exception. On the other hand, C++ includes support for language exceptions.
- Scanf() and printf() are the most often used input and output in C. In C++, cin will be the standard stream of input while cout is the standard stream of output.
- While C is a language for procedural programming, C++ offers protocol and object-oriented programming capabilities.
Explain why we need the Friend class and function?
Answer: Sometimes a certain class needs to have access to secret or protected class members. The solution is a class of friends, who can enter the secret and secure classrooms in which they are proclaiming friends. Like a friend’s lesson, a friend’s function allows private and protected members of the class. A friend function might be a global function or a class method.
Some essential things concerning class and friend function:
- There’s no inherited friendship.
- A program should restrict the total number of classes and functions since the overflow of these classes might lead to a depreciation of the idea of encapsulation of distinct classes which represents an intrinsic and desired characteristic of object-oriented programming.
Could you explain the significance of vTable and vptr in C++ and how the compiler deals with them?
Answer: VTable is a function pointer table. The vTable is available in every class. vptr is a vTable pointer. There’s one vptr in every object. The C++ compiler provides two extra areas of code to maintain and use vptr and vTable:
- Each builder — This code specifies vptr:
- The generated item.
- To indicate the class table.
- Code with a polymorphic functional call — The compiler adds the vptr code with the base class pointer or reference for each polymorphic call. The vTable of the derived class is available once successfully selected. Accessed and called by vTable is the address of the derived class method display().
How is Function Overloading different from Operator Overloading?
Answer: Function overloading enables to have the same names for two or more functions of various kinds and arguments. Operator overloading, on the other hand, enables the redefinition of how an operator functions for a defined type.
Would you define the default constructor?
Answer: In case the supplier doesn’t supply the same, the compiler offers a constructor for every class. This is when the programmer gives the builder no particular settings other than the default builder. The default builder code can be like the example below.
Explain a comparison between C++ and Java?
- When an object destroyed, C++ provides destroyers that come automatically. Java is famous for its automatic garbage collection.
- Multiple inheritances, overloading of operators, pointers, and unions support C++. None of them has Java.
- Java has an inherited thread class for creating a new thread. C++ does not have embedded thread support.
- A goto statement in C++ gives the means to go to some designated statement in the same function from one position. No goto statement is available in Java.
- Run and build C++ using the compiler to transform the source code into the level language of the machine. So, it depends on the platform. On the other hand, the Java compiler transforms source code into platform-independent JVM bytecode.
Would you Explain Virtual Functions and the concept of Runtime Polymorphism in C++ with a code example?
Answer: Every virtual keyword accompanying function has a virtual function’s behavior. In contrast to conventional functions which are according to the kind of point of reference used, virtual functions are in need according to the type of object referenced or pointed. Virtual features solve in simple words during runtime, not sooner. Also, it may be understandable that the use of virtual functions is to write a C++ program using the runtime polymorphic concepts. Important things in C++ for developing a virtual feature are:
- A basic class.
- A class derived.
- In both the base and the derived classes, a function has the same name.
- A base class type pointer or reference that points or references to an object of the derived class, respectively.
The usage of virtual functions (or runtime polymorphism in play) is an example of this:
A pointer of type Base is in the above program bp. The display() method of the Derived class has a name which is bp->show(). Bp points to an object of the class derived.
Acing C++ job interview questions need optimal preparation. For this specific reason, we built Huru. Huru is an application that aims to prepare job hunters precisely to nail any type of job interview through simulated interviews and in-depth analysis. Besides, Huru’s breakthrough technology provides job seekers with timed and scored, and personalized interviews that provide real-time insights for more effective preparation.
At the bottom line, These C++ interview questions have been carefully prepared by the recruiting professionals in the sector for years. Professional hiring managers and engineers put their pride in answering each C++ interview question presented in this article. But, it would do you no hurt if you conduct some more research about other C++ interview questions.
You may have noticed that these C++ interview questions are not what you’ve seen before. It is exactly the same as in an actual interview when your interviewer is looking for a programmer who is able to think like a software engineer and effectively solve the problems as if they were coding a real code rather than memorizing canned questions and answers. These C++ interview questions come from real-time C++ job interviews at Google, Microsoft, Amazon, Facebook, etc.