Top 35 C++ Interview Questions and Answers

C Interview Questions and Answers

C++ stands as a versatile anowerful programming language, renowned for its object-oriented capabilities and performance. It extends upon the C language, offering additional features like classes, templates, and exception handling, rendering it ideal for creating intricate and efficient applications. Widely used across software development, game development, system programming, and more, mastering C++ is pivotal for excelling in various domains.

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To excel in C++ programming interviews, adhere to the following expert guidance:

  1. Master the Basics: Cement a robust understanding of fundamental concepts such as pointers, data types, loops, and functions. Acquaint yourself with standard libraries to efficiently resolve common programming hurdles.
  2. OOP Concepts: Attain proficiency in Object-Oriented Programming (OOP) principles like inheritance, polymorphism, and encapsulation. Apply these principles adeptly in designing and implementing resilient solutions.
  3. Practice Problem Solving: Hone your problem-solving skills by tackling a diverse array of C++ coding problems. Engage in coding contests and challenges to gain exposure to various scenarios and enhance your proficiency.
  4. Memory Management: Grasp the nuances of memory management in C++ to prevent memory leaks and optimize resource utilization. Familiarize yourself with smart pointers and adhere to the RAII (Resource Acquisition Is Initialization) principles.
  5. Algorithms and Data Structures: Refresh your knowledge of essential algorithms and data structures, including sorting, searching, linked lists, trees, and graphs. A strong foundation in these areas will enable you to tackle intricate interview questions effectively.
  6. Practice Interview Questions: Devote time to practicing specific C++ interview questions commonly posed during interviews. Cover topics such as virtual functions, operator overloading, templates, and exception handling to ensure readiness for any challenge.

By adhering to these strategies and honing your skills diligently, you’ll be well-equipped to tackle C++ programming interviews with confidence and expertise.

C++ Interview Questions For Freshers

1. What are the different data types present in C++?

Primitive, abstract, and derived data types are the three forms of data that exist in C++. Integer, floating-point, character, boolean, double floating-point, valueless or void, and wide character are examples of primitive data types.

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

Because C is a procedural programming language, it is a function-driven language. Because it uses object-oriented programming, C++ is a language driven by objects. In C, overloading of functions and operators is not supported. C++ supports function and operator overloading.

3. What are class and object in C++?

A user-defined data type called a class has member functions and data members. The data variables are known as data members, and the methods used to manipulate these variables are known as member functions.

A class’s instances are objects. An object can alternatively be referred to as a variable of a class since a class is a user-defined data type.

4. What is the difference between struct and class?

The only difference between the two constructs in C++ is that classes have a default accessibility of private, whereas structs have a default accessibility of public. The building blocks via which you define your own types are classes and structs.

5. What is operator overloading?

Programmers can utilise notation more closely related to the target domain thanks to operator overloading in C++. They offer comparable support for user-defined types as built-in types do. In C++, operator overloading facilitates programme comprehension.

6. What is polymorphism in C++?

In C++, polymorphism refers to the concept of a same entity (function or object) behaving differently under various conditions. Think of this illustration: When used with numbers, the “+” operator in C++ conducts addition. When used with other types of data, it does multiplication.

The two types of polymorphism in c++ are:

  • Compile Time Polymorphism
  • Runtime Polymorphism

7. Explain constructor in C++?

When an object of a class is created in C++, the member functions called constructors are called. Default, parameterized, and copy constructors are the three basic types of constructors in C++.

8. Tell me about virtual function

In order to create polymorphism in C++, a virtual function is a base class member function that can be redefined in a derived class. The virtual keyword can be used to declare the function in the base class.

9. Compare compile time polymorphism and Runtime polymorphism?

Resolving the method call at compile time is possible with compile-time polymorphism (static binding). Runtime polymorphism is resolved at runtime by the JVM (dynamic binding).

10. What do you know about friend class and friend function?

A friend class can access private, protected, and public members of other classes in which it is declared as friends.

Like friend class, friend function can also access private, protected, and public members. But, Friend functions are not member functions.

11. What are the C++ access specifiers?

There are three access specifiers in C++: Members can be accessed by others outside the class. Members cannot be accessed (or viewed) from outside the class if they are private. protected members can be accessed in inherited classes but cannot be accessed from outside the class.

12. Define inline function

When a function is inlined, the compiler inserts a duplicate of that function’s code at each location where it is called during compilation. The elimination of function calling overhead compared to utilising a standard function is one of the key benefits of employing an inline function.

13. What is a reference in C++?

Reference variable is another name for a variable that already exists. It should be initialised at the moment of declaration, cannot be NULL, and cannot be altered to refer to another variable. Reference variables are declared using the & operator.

14. What do you mean by abstraction in C++?        

Abstraction refers to hiding the intricacies and presenting simply the most important facts. Data abstraction is the process of exposing to the outside world only the information that is absolutely necessary while concealing implementation or background information.

15. Is deconstructor overloading possible? If yes then explain and if no then why?

Overloading a destructor is not feasible. There is just one way to destroy an object because destroyers don’t accept any parameters. Destructor overloading is not feasible because of this.

16. What do you mean by call by value and call by reference?

Call by Value refers to using a parameter’s value when invoking a method. The argument value is provided to the parameter in this way. Calling a method using a parameter as a reference is known as calling by reference. The parameter receives the argument reference through this.

17. What is an abstract class and when do you use it?

A class that is explicitly intended to be used as a base class is known as an abstract class. There is at least one pure virtual function in an abstract class. In the declaration of a virtual member function in the class declaration, you declare a pure virtual function by using the pure specifier (= 0).

18. What are destructors in C++?

An object’s destructor is a member function that is automatically called when it exits its scope or when it is specifically destroyed by a call to delete. the the, the, by . the by the, a by the by the by the For instance, the class String’s destructor is declared as String().

19. What are the static members and static member functions?

Class members that are declared with the static keywords are known as static data members. A static member has a few unique qualities. Which are: No matter how many objects are produced, only one copy of that member is made for the entire class and shared by all of the objects.

Even if the class’s objects don’t exist, a static member function can still be accessible by using the class name and the scope resolution operator.

20. Explain inheritance

One of the four cornerstones of object-oriented programming is inheritance (OOPs). A class can acquire the traits and properties of another class thanks to this functionality. Because the derived class or the child class can reuse the members of the base class by inheriting them, inheritance enables code reuse.

C++ Interview Questions For Experienced

21. What is a copy constructor?

A copy function Object() { [native code] } is a member function that uses another object from the same class to initialise a new object. A copy function Object() { [native code] } is, to put it simply, a function Object() { [native code] } that produces an object by initialising it with a different object of the same class that has already been constructed.

22. What is the difference between shallow copy and deep copy?

While pointing references to the objects, shallow copy stores a copy of the original item. Recursively copying the items while storing a duplicate of the original object is known as deep copy.

23. What is the difference between virtual functions and pure virtual functions?

A member function from the base class that you redefine in a derived class is known as a virtual function. Utilizing the virtual keyword, it is proclaimed.

A function that is declared by assigning a value of 0 and has no implementation is known as a pure virtual function. It is bodyless.

24. If class D is derived from a base class B. When creating an object of type D in what order would the constructors of these classes get called?

A base portion and a derived part make up the derived class. the the an an an an an an an an an an an a. the s of The most basic class, located at the top of the inheritance tree, is created first. Then, up until the most-child class is constructed last, each child class is constructed one at a time.

So, after calling the first function Object() { [native code] } of class B, class D’s function Object() { [native code] } will be called.

The demolition is carried out in precise reverse order. That is, the destructor works its way down from the most-derived class to the base class.

As a result, class D’s first destructor will be called before class B’s destructor.

25. Can we call a virtual function from a constructor?

A virtual function may be called in a function Object() { [native code] }, but exercise caution. It might not perform as expected. The virtual call mechanism in a function Object() { [native code] } is disabled since overriding from derived classes hasn’t happened yet. The phrase “base before derived” refers to the way that objects are built.

26. What are void pointers?

A pointer with no associated data type is referred to as a void pointer. Any type of address can be stored in and typecast to a void pointer.

  1. What is this pointer in C++?

Every object has a pointer called this that points to the object itself in the member functions. The address of the object for which it is called is set as the value of this. The data in the object it points to can be accessed using it.

28. How do you allocate and deallocate memory in C++?

In C++, the new operator is used to allocate memory, whereas the deletes operator is used to deallocate memory.

30. What is a mutable storage class specifier? How can it be used?

Only the non-static and non-constant member variables of the class can be specified with a mutable storage class specifier. By declaring it, the member of the constant class object can be changed. You can accomplish this by employing a storage class specifier.

The mutable specifier is incompatible with names that are defined as static, const, or reference members.

31. Can we have a string primitive data type in C++?

A data type is considered primitive if the values it may represent are simple (a number, a character, or a truth value). The foundation for more sophisticated data types is provided by primitive types, which are the most fundamental building blocks for any computer language.

In C++, there is no such thing as a String Primitive data type. We can substitute a class from the Standard Template Library instead (STL).

32. What is the function of scope resolution operator in C++?

The out-of-scope global variable or member function is referred to by the scope resolution operator. The symbol for it is a double colon (::).

The scope resolution operator can perform the following tasks:

They aid in determining the range of different global variables.

A function enables association with the class when it is defined outside the class.

33. What are the C++ tokens?

In general, a token is an item that stands in for another thing, such as another thing (physical or virtual) or an abstract idea, like a gift, and is frequently referred to as a sign of respect from the donor to the recipient.

In C++ programming, some functions are referred to as tokens. A keyword, symbol, string literal, identifier, constant, etc. are examples of tokens.

34. What is the diamond problem?

The diamond problem in C++, which illustrates the difficulty of the programming language to enable hybrid inheritance using multiple and hierarchical inheritances, arises when two superclasses of a class share a base class.

35. What is a block scope variable?

A variable defined as a block in C++ can be declared anywhere within the block and is used to define a variable within a block of code, such as a for loop or an if statement.

36. How is the data hiding concept achieved in C++?

Access specifiers specify the methods and attributes of a class that can be accessed.

By defining user-defined types known as classes, C++ provides data hiding and, consequently, data abstraction and encapsulation. Access specifiers, a type of keyword, are used to limit the scope of members of this produced class.

37. What is a “translation unit” in C++?

The fundamental building block of C++ compilation is a translation unit. This unit is the result of preprocessing of the contents of a single source file. Any header files lacking blocks that are disregarded by conditional preprocessing statements like ifdef, ifndef, etc. are included in it.

In conclusion, this comprehensive guide on C++ interview questions and answers serves as a valuable resource for job seekers and interviewers looking to excel in C++ interviews. Covering a wide range of C++ topics, from fundamental concepts to advanced programming techniques, this guide equips individuals with the knowledge and confidence needed to succeed. By exploring this resource, you can strengthen your understanding of C++, improve your programming skills, and confidently tackle C++ interview questions. Whether you’re a seasoned C++ developer or new to the language, this guide provides valuable insights to enhance your C++ expertise and excel in your interviews.

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