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Top C++ Interview Questions

Top C++ Interview Questions

C++ Interview

Undoubtedly, C++ is an important programming language. Software companies require professionals with in-depth knowledge of C++. To achieve success in C++ interview, you have to demonstrate your skills and command over programming. 

The interviewers may give you a problem to solve, or you may have to write code to indicate that you are well-versed in this language. In the interview, the questions aim to evaluate your fundamental concepts about this language. 

Following are the questions that interviewers tend to ask in C++ interview:

1. How Do you Define C++?

Answer: It is a computer-programming language, which is the advanced form of C. However, it has several additional features, and that is why it is OOPS (Object Oriented Programming System). 

It refers to a model that supports an application of different concepts such as polymorphism, data-binding, and others. 

2. Describe the term “Inheritance” in C++

Answer: C++ enables classes to inherit a few typical characteristics from different classes. This procedure is inheritance. 

3. What is the Concept of Class in Object in C++?

Answer: An object is a form of the class. The object consists of methods, fields, and constructors. For instance, a vehicle in practical life is an object but has different characteristics such as accelerator, brakes, model, and others are examples of a class. 

4. What is the Concept of Encapsulation in C++?

Answer: Encapsulation is the method of connecting the data and functions in the class. The process ensures that data is not directly accessible for security purposes.

 For instance, the internet banking feature for the clients only allows authorized individuals with login and password to have access. The user can only access their information through the login and password. 

5. How Do you Define Abstraction in C++?

Answer: Through Abstraction, the program hides the internal procedures, and only shows the relevant or required information. For example, when users deliver email from their account to the recipient id, the system displays the written content and the “send” option alongside other options. 

When the user finishes clicking the “send” button, they see the message that the system has sent their message. However, the system does not display the internal processes that transfer data from point to the other. 

6. How do you define the Concept of the Keyword “Volatile?”

Answer: It is a function, which helps in pointing out that a specific variable is volatile. Hence, it instructs the compiler to alter the variable from outside. 

7. Describe Storage Class in C++ Language, and Provide a Few Names

Answer: The storage class in C++ particularly deals with the symbols; it also includes functions, variables and others. Static, auto, register, mutable, extern and others. 

8. Is Recursive Inline Function Possible in C++?

Answer: Although it is possible to have an inline function within C++, the compiler might not create the inline code. 

The reason behind not generating the inline code is that the compiler would not figure out the detail of recursion at the time of compilation. 

9. Describe an Inline Function in C++

Answer: To minimize the function overhead, the C++ generates inline functions. When the user calls an inline function, it expands in a line. The moment the user calls the inline function, the alteration or substitution of the entire code takes place at the specific location of the inline service. 

At the time of compilation, the C++ compiler completes the process of substitution. The program efficiency may improve due to small inline functions. 

10. What is “this” Pointer?

Answer: It refers to a constant pointer, and it keeps the memory address of the present object. It works as a concealed argument to every non-static member function call. 

Additionally, it is present as a local variable inside the body of every non-static function. The system can call static member functions without an object. It means by the class name, “this” pointer does not exist for them. 

11. Why Do Programmers Require the Friend Class and Function?

Answer: At times, programmers need to allow a specific class to access protected or private members of the course. So, friend class serves this purpose because it has the tendency to access the private alongside protected members of a class, in which they declare it as a friend. 

Likewise, there is a friend function, which can access both protected and private class members. The friend function may also be a global function or a procedure of a class. 

Following are some essential features of friend function and class

  • There is no inheritance of friendship 
  • Friendship is not ordinary; it does not become the friend of a friend-class
  • The number of friend functions and classes has a limit in the program because excess may cause the depreciation of the encapsulation notion about different classes, which is a fundamental and preferable object-oriented programming feature. 

12. What Is the Importance of V-table and V-ptr in C++, and How the Compiler Handles Them?

V-table is a table which consists of a function pointer. Each class contains v-table. Furthermore, v-ptr refers to the tip of v-table. Every object consists of a v-ptr. To maintain and use v-table and v-ptr, the compiler employs extra code in two locations. 

For every constructor, the code sets v-ptr of the object being formed. Similarly, the code with the polymorphic function call is essential. At all the places where there is a polymorphic call, the compiler puts the system to find v-ptr with the help of reference or base class pointer. 

The v-table of the derived class is accessible at the time when the process of fetching v-ptr is complete. The derived class function’s address “show ()” is available, and programmers call it with the help of vtable. 

13. What Is the Difference Between Operator Overloading and Function Overloading?

Operator overloading enables redefining how the operator acts about user-defined types. 

On the other hand, function overloading enables two or more functions having various types and parameter to share the same name. 

Final Word

In the C++ interview, you have to demonstrate your knowledge about the concepts of this language. Along with answers, the interviewers may require you to quote specific examples. The questions mentioned above give you an overview of C++ interview. 

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