C++ Interview Questions and Answers, C++ Interview Questions and Answers Freshers, C++ Interview Questions and Answers, C++ Interview Questions

Before getting on to the C++ interview questions, the student must know that the C++ is a continuously varying field which needs the students as well as professionals to upgrade their skills with the new features and knowledge, to get fit for the jobs associated with C++. This post related to C Interview Questions and Answers, C++ Interview Questions and Answers Freshers, C++ Interview Questions and Answers, C++ Interview Questions will help you let out find all the solutions that are frequently asked in you upcoming C++ interview.

Over thousands of vacancies available for the C++ developers, experts must be acquaintance with all the component of C++ technologies. This is necessary for the students in order to have in-depth knowledge of the subject so that they can have best employment opportunities in the future. Knowing every little detail about C++ is the best approach to solve the problems linked with problem.

APTRON has spent hours and hours in researching about the C++ Interview Questions and Answers, C++ Interview Questions and Answers Freshers, C++ Interview Questions and Answers, C++ Interview Questions that you might encounter in your upcoming interview.  All these questions will alone help you to crack the interview and make you the best among all your competitors.

First of all, let us tell you about how the C++ technology is evolving in today’s world and how demanding it is in the upcoming years. In fact, according to one study, most of the companies and businesses have moved to the C++. Now, you cannot predict how huge the future is going to be for the people experienced in the related technologies.

Hence, if you are looking for boosting up your profile and securing your future, C++ will help you in reaching the zenith of your career. Apart from this, you would also have a lot of opportunities as a fresher.

These questions alone are omnipotent. Read and re-read the questions and their solutions to get accustomed to what you will be asked in the interview. These C++ interview questions and answers will also help you on your way to mastering the skills and will take you to the giant world where worldwide and local businesses, huge or medium, are picking up the best and quality C++ professionals.

This ultimate list of best C++ interview questions will ride you through the quick knowledge of the subject and topics like Data Types and Variables, Arrays, Pointers, Control-Flow Statements,Operands, Operators. This C++ interview questions and answers can be your next gateway to your next job as a C++ expert.

These are very Basic C++ Interview Questions and Answers for freshers and experienced both.

Q1: What is C++?
A1: C++ is an object oriented programming language created by Bjarne Stroustrup. It is released in 1985.

Q2: What are the advantages of C++?
A2: C++ doesn’t only maintains all aspects from C language, it also simplify memory management and add several features like:

  • Includes a new datatype known as a class.
  • Allows object oriented programming.

Q3: What is the difference between C and C++?

No. C C++
1) C follows the procedural style programming. C++ is multi-paradigm. It supports both procedural and object oriented.
2) Data is less secured in C. In C++, you can use modifiers for class members to make it inaccessible for outside users.
3) C follows the top-down approach. C++ follows the bottom-up approach.
4) C does not support function overloading. C++ supports function overloading.
5) In C, you can’t use functions in structure. In C++, you can use functions in structure.
6) C does not support reference variables. C++ supports reference variables.
6) In C, scanf() and printf() are mainly used for input/output. C++ mainly uses stream cin and cout to perform input and output operations.

Q4: What is a class
A4: Class is a user-defined data type. Class defines the type definition of category of things. It defines a datatype, but it does not define the data it just specifies the structure of data.

You can create N number of objects from a class.

Q5: What is an object?
A5: Object is the instance of a class. A class provides a blueprint for objects. So you can create an object from a class. The objects of a class are declared with the same sort of declaration that we declare variables of basic types.

Q6: What is this pointer?
A6: The ‘this’ pointer is passed as a hidden argument to all nonstatic member function calls and is available as a local variable within the body of all nonstatic functions. ‘this’ pointer is a constant pointer that holds the memory address of the current object. ‘this’ pointer is not available in static member functions as static member functions can be called without any object (with class name).

Q7: What are VTABLE and VPTR?
A7: vtable is a table of function pointers. It is maintained per class.

vptr is a pointer to vtable. It is maintained per object (See this for an example).

Compiler adds additional code at two places to maintain and use vtable and vptr.

1) Code in every constructor. This code sets vptr of the object being created. This code sets vptr to point to vtable of the class.

2) Code with polymorphic function call (e.g. bp->show() in above code). Wherever a polymorphic call is made, compiler inserts code to first look for vptr using base class pointer or reference (In the above example, since pointed or referred object is of derived type, vptr of derived class is accessed). Once vptr is fetched, vtable of derived class can be accessed. Using vtable, address of derived derived class function show() is accessed and called.

Q8: What is encapsulation?
A8: The process of binding the data and the functions acting on the data together in an entity (class) called as encapsulation.

Q9: What is abstraction?
A9: Abstraction refers to hiding the internal implementation and exhibiting only the necessary details.

Q10: What is inheritance?
A10: Inheritance is the process of acquiring the properties of the exiting class into the new class. The existing class is called as base/parent class and the inherited class is called as derived/child class.

Q11: Explain the purpose of the keyword volatile.
A11: Declaring a variable volatile directs the compiler that the variable can be changed externally. Hence avoiding compiler optimization on the variable reference.

Q12: What is an inline function?
A12: A function prefixed with the keyword inline before the function definition is called as inline function. The inline functions are faster in execution when compared to normal functions as the compiler treats inline functions as macros.

Q13: What is a storage class?
A13: Storage class specifies the life or scope of symbols such as variable or functions.

Q14: What is implicit conversion/coercion in c++?
A14: Implicit conversions are performed when a type (say T) is used in a context where a compatible type (Say F) is expected so that the type T will be promoted to type F.

short a = 2000 + 20;

In the above example, variable a will get automatically promoted from short to int. This is called implicit conversion/coercion in c++.

Q15: What do you mean by translation unit in c++?
A15: We organize our C++ programs into different source files (.cpp, .cxx etc). When you consider a source file, at the preprocessing stage, some extra content may get added to the source code ( for example, the contents of header files included) and some content may get removed ( for example, the part of the code in the #ifdef of #ifndef block which resolve to false/0 based on the symbols defined). This effective content is called a translation unit. In other words, a translation unit consists of

  • Contents of source file
  • Plus contents of files included directly or indirectly
  • Minus source code lines ignored by any conditional pre processing directives ( the lines ignored by #ifdef,#ifndef etc)

Q16: What do you mean by storage classes?
A16: Storage class are used to specify the visibility/scope and life time of symbols(functions and variables). That means, storage classes specify where all a variable or function can be accessed and till what time those variables will be available during the execution of program.

Q17: What do you mean by persistent and non persistent objects?
A17: Persistent objects are the ones which we can be serialized and written to disk, or any other stream. So before stopping your application, you can serialize the object and on restart you can deserialize it. [ Drawing applications usually use serializations.]
Objects that can not be serialized are called non persistent objects. [ Usually database objects are not serialized because connection and session will not be existing when you restart the application. ]

Q18: Is it possible to get the source code back from binary file?
A18: Technically it is possible to generate the source code from binary. It is called reverse engineering. There are lot of reverse engineering tools available. But, in actual case most of them will not re generate the exact source code back because many information will be lost due to compiler optimization and other interpretations.

Q19: Explain what is multi-threading in C++?
A19: To run two or more programs simultaneously multi-threading is useful. There are two types of

  • Process-based: It handles the concurrent execution of the program
  • Thread-based: It deals with the concurrent execution of pieces of the same program

Q20: Explain what is upcasting in C++?
A20: Upcasting is the act of converting a sub class references or pointer into its super class reference or pointer is called upcasting.

Q21: Explain what is pre-processor in C++?
A21: Pre-processors are the directives, which give instruction to the compiler to pre-process the information before actual compilation starts.

Q22: Explain what is COPY CONSTRUCTOR and what is it used for?
A22: COPY CONSTRUCTOR is a technique that accepts an object of the same class and copies its data member to an object on the left part of the assignment.

Q23: Explain what is data encapsulation in C++?
A23: Encapsulation is an object oriented programming concept (oops) which binds together the data and functions. It is also referred as data hiding mechanism.

Q24: Mention what are the types of Member Functions?
A24: The types of member functions are

  • Simple functions
  • Static functions
  • Const functions
  • Inline functions
  • Friend functions

Q25: What Is Dangling Pointer?
A25: These are the pointers that do not point to any object of appropriate type. These are special cases of memory vialation as they do not point to any appropraite type.These arises when some object is deleted from the memory or when an object is deallocated thus the pointer keeps on pointin to the memory location untill it is modified. Dangling pointers may lead to unpredictable results.

Q26: What Do You Know About Near, Far And Huge Pointer?

  • A near pointer is a 16 bit pointer to an object which is contained in the current segment like code segment, data segment, stack segment and extra segment. It holds only offset address.
  • A far pointer is a 32 bit pointer to an object anywhere in memory. It can only be used when the compiler allocates a segment register, or we can say the compiler must allocate segment register to use far pointers. These pointers hold 16 bit segment and 16 bit offset address.
  • Huge pointers are also far pointers i.e. 32 bit pointer the difference is that the huge pointer can be increased or decreased uniformly between any segments and can have any value from 0 to 1MB.

Q27: What Is Null Pointer?
A27: NULL pointer is not the unitialised pointer that can point anywhere, the NULL pointers are the one which do not point anywhere that is which do not point to any object or any function.

Q28: How can we access protected and private members of a class?
A28: In the case of members protected and private, these could not be accessed from outside the same class at which they are declared. This rule can be transgressed with the use of the friend keyword in a class, so we can allow an external function to gain access to the protected and private members of a class.

Q29: What do you mean by late binding?

  • Late binding refers to function calls that are not resolved until run time.
  • Virtual functions are used to achieve late binding.
  • When access is via a base pointer or reference, the virtual function actually called is determined by the type of object pointed to by the pointer.

Q30: What do you mean by early binding?

  • Early binding refers to the events that occur at compile time.
  • Early binding occurs when all information needed to call a function is known at compile time.
  • Examples of early binding include normal function calls, overloaded function calls, and overloaded operators.
  • The advantage of early binding is efficiency.

C++ Conclusion Interview FAQs

We know the list of C++ Interview Questions and Answers, C++ Interview Questions and Answers Freshers, C++ Interview Questions and Answers, C++ Interview Questions is overwhelming but the advantages of reading all the questions will maximize your potential and help you crack the interview. The surprising fact is that this C++ interview questions and answers post covers all the basic of the C++ technology and you have to check out the FAQs of different components of C++ too.

However, you will be asked with the questions in the interview related to the above mentioned questions. Preparing and understanding all the concept of C++ technology will help you strengthen the other little information around the topic.

After preparing these interview questions, we recommend you to go for a mock interview before facing the real one. You can take the help of your friend or a C++ expert to find the loop holes in your skills and knowledge. Moreover, this will also allow you in practicing and improving the communication skill which plays a vital role in getting placed and grabbing high salaries.

Remember, in the interview, the company or the business or you can say the examiner often checks your basic knowledge of the subject. If your basics is covered and strengthened, you can have the job of your dream. The industry experts understand that if the foundation of the student is already made up, it is easy for the company to educate the employ towards advance skills. If there are no basics, there is no meaning of having learnt the subject.

Therefore, it’s never too late to edge all the basics of any technology. If you think that you’ve not acquired the enough skills, you can join our upcoming batch of C++ Training in Noida. We are one of the best institute for C++ in noida which provide advance learning in the field of C++ Course. We’ve highly qualified professionals working with us and promise top quality education to the students.

We hope that you enjoyed reading C++ Interview Questions and Answers, C++ Interview Questions and Answers Freshers, C++ Interview Questions and Answers, C++ Interview Questions and all the FAQs associated with the interview. Do not forget to revise all the C++ interview questions and answers before going for the C++ interview. In addition to this, if you’ve any doubt or query associated with C, you can contact us anytime. We will be happy to help you out at our earliest convenience. At last, we wish you all the best for your upcoming interview on C++ Technology.