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The 9 Best C++ Interview Questions in 2023

What are the top C++ interview questions? Today, you get the top questions to ask at your next interview. Want to learn more? Read on!

Interviewing C++ developers 

C++ is a general-purpose, high-level programming language. It was originally created as an extension of C. However, today C++ has object-oriented, generic, and functional features, as well as facilities for low-level memory manipulation. 

C++ is almost always implemented as a compiled language. It was defined with systems programming and embedded, resource-constrained software and large systems in mind. Some of its design highlights include performance, efficiency, and flexibility. C++ is also frequently used as part of desktop applications, video games, servers, and performance-critical applications. 

But how do you find the right C++ candidates? Here’s what you need to know about the top C++ interview questions. 

Beginner C++ interview questions

What are some great interview questions for junior C++ developers? Here are some of our favorites: 

1. What are the benefits of C++? 


C++ is a highly portable language, meaning the software developed with C++ can be used on any platform. It’s also an object-oriented language and includes concepts like classes, objects, inheritance, abstraction, and polymorphism. 

C++ has inheritance so that you can eliminate redundant code and reuse existing classes. Data hiding also helps developers to build secure programs. Message passing supports communication between objects and C++ contains a rich function library. 

2. What data types are there in C++? 


There are four data types in C++. These are: 

  • Primitive Datatype, such as short, int, float, and double.

  • Derived datatype, such as array and pointer.

  • Enumeration, such as enum.

  • User-defined data types, such as structure and class. 

3. What are scopes in C++?


A scope is an area where the variable is active. The variable in scope can be declared, defined, and used. C++ has two types of scopes: 

  • Local scope: If the variable is declared within a block of code and is only active inside the block, it’s in a local scope and is accessible outside the block. 

  • Global scope: If a variable is declared at the top of a program, it’s in a global scope and is accessible throughout the program. 

4. Explain the C++ OOPs concept. 


OOPs stands for object-oriented programming. It’s an approach where the programs are structured around objects instead of logic or functions and parts data into two memory areas–data and functions. 

OOPs includes: 

  • Objects: An object is an instance of a class. 

  • Class: The collection of objects is called a class. A class is defined in C++ using keyword class followed by the name of the class. 

  • Inheritance: Those properties of the parent class inherited into child class are known as inheritance. 

  • Encapsulation: Encapsulation refers to the binding of code and data together into a single unit. 

  • Abstraction: Abstraction refers to the hiding of internal details and showing functionalities to the user. 

5. What are the three access specifiers in C++? 


Access specifiers are defining code elements that can determine which elements of a program are allowed to access a variable or other data. In C++, there are three: 

  • Public: All member functions and data members are accessible outside the class. 

  • Protected: All member functions and data members are accessible within the class and to the derived class.

  • Private: Member functions and data members can’t be accessed outside of the class. 

Advanced C++ interview questions

What are some advanced C++ interview questions? Read on for some of the top senior C++ interview questions. 

6. Explain how the assignment operator ( = ) is different from the equal to operator ( == ). 


Assignment operator assigns the value to the variable. It’s sometimes used in complex equations. On the other hand, the equal to operator is an equality operator that is used to compare two values. If they are equal, the operator returns true. Otherwise, it returns false. 

7. Explain the difference between delete and delete[]. 


Delete is used to release a chunk of memory, which has been allocated using new. Delete[], on the other hand, is used to release the array allocated memory, which has been allocated using new[].

8. Explain the “diamond problem” that occurs with multiple inheritance in C++. 


The diamond problem refers to the inability of C++ to support hybrid inheritance with multiple and hierarchical inheritance. 

The problems arise in terms of inheritance from Person classes. The Person class defines an abstract getRole() method that’s overridden by its subclasses in order to return the correct role type. General roles inherit from the same Person class. If the role is hybrid, the problem generates an inheritance diagram in the shape of a diamond. 

9. Can you have a recursive inline function? 


You can call an inline function from within itself, but the compiler can't generate inline code as it can’t determine the depth of recursion at compile time. A compiler with a good optimizer can inline recursive calls to some depth fixed at compile time. It can insert non-recursive calls at compile time when the depth exceeds at run time. 

Over to you!

There you have it! Now you know what the top C++ interview questions are. 

However, interviews are one part of your hiring process. You also need to assess your candidates.

How? With assessment tests. And that’s where CodeSubmit can support you. 

We offer some of the top C++ assessment tests for developers.

Want to learn more?

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