Top 10 C++ Developer Interview Questions & Answers in 2024

1. Explain the differences between C++11, C++14, C++17, and C++20, highlighting key features introduced in each standard.

C++11 introduced features like auto keyword, lambda expressions, and smart pointers. C++14 focused on bug fixes and minor improvements. C++17 introduced features like std::optional and std::variant. C++20 brought concepts, ranges, and coroutines.

2. Discuss the concept of RAII (Resource Acquisition Is Initialization) in C++. Provide examples of how RAII is applied in real-world scenarios.

RAII is a C++ programming paradigm where resource management is tied to object lifetime. Common examples include using smart pointers for dynamic memory management and file handling with ifstream/ofstream. RAII ensures that resources are released automatically when objects go out of scope.

3. Describe the differences between shallow copy and deep copy in C++, and discuss scenarios where each is appropriate.

Shallow copy creates a new object but shares the underlying data with the original object. Deep copy creates a new object and duplicates the underlying data. Shallow copy is efficient but can lead to unintended side effects. Deep copy ensures data independence but can be resource-intensive. Choose based on use case and performance considerations.

4. Explain the purpose of the 'const' keyword in C++ and its various use cases.

'const' in C++ is used to specify that a variable or function won't be modified. It ensures compile-time immutability, facilitates compiler optimizations, and enhances code readability. 'const' can be applied to variables, member functions, function parameters, and pointers.

5. Discuss the differences between the stack and heap memory in C++. When would you use one over the other?

Stack memory is fast but limited in size, used for local variables and function call management. Heap memory is dynamic, allowing for larger data, but requires manual memory management using 'new' and 'delete'. Use stack for small, short-lived data, and heap for dynamic, long-lived data.

6. Implement a custom smart pointer in C++. Discuss the advantages of using smart pointers over raw pointers.

A custom smart pointer involves implementing a class with overloaded operators for pointer-like behavior. Smart pointers manage memory automatically, preventing memory leaks and improving code safety. They provide automatic destruction, ownership semantics, and better exception safety.

7. Explain the purpose of move semantics in C++. Provide examples of when and how to use std::move.

Move semantics enable efficient transfer of resources (like memory ownership) from one object to another. std::move converts an object into an rvalue, facilitating move operations. Use move semantics when transferring resources or optimizing performance, especially in containers and smart pointers.

8. Discuss the role of templates in C++ and provide an example of a template class or function.

Templates in C++ enable generic programming by allowing the creation of generic classes or functions. For example, a template class might be a generic container like std::vector, adaptable to various data types. Templates increase code reusability and flexibility.

9. Explain the concept of multithreading in C++. Provide examples of how to create and synchronize threads.

Multithreading in C++ allows concurrent execution of tasks. Use std::thread to create threads and std::mutex for synchronization. Ensure proper locking mechanisms to prevent data races. Consider thread-safe data structures and the use of std::async for asynchronous tasks.

10. Describe the principles of the C++ Standard Library. Provide examples of commonly used containers and algorithms.

The C++ Standard Library provides a set of generic templates, algorithms, and containers. Examples of containers include std::vector and std::map. Algorithms like std::sort and std::find operate on these containers. Utilize the library for efficient and standardized data manipulation in C++.