Top 44 C++ Interview Questions & Answers (2026)

01 What is C++ and how does it differ from C? 02 What are the four pillars of OOP in C++? 03 What is a class and an object in C++? 04 What are constructors and destructors in C++? 05 What is the difference between new/delete and malloc/free in C++? 06 What are pointers and references in C++? 07 What is function overloading in C++? 08 What is inheritance in C++? 09 What are virtual functions and polymorphism in C++? 10 What are access specifiers in C++? 11 What is the Standard Template Library (STL)? 12 What are templates in C++? 13 What are smart pointers in C++? 14 What is the difference between stack and heap memory in C++? 15 What are namespaces in C++? 16 What are lambda expressions in C++? 17 What is the const keyword in C++? 18 What is RAII in C++? 19 What is exception handling in C++? 20 What are iterators in C++?

01 What is move semantics in C++? 02 What are lvalues and rvalues in C++? 03 What is the Rule of Three/Five/Zero in C++? 04 What is template specialization and SFINAE in C++? 05 What is std::vector and how does it work internally? 06 What is std::map vs std::unordered_map? 07 What is operator overloading in C++? 08 What is multithreading in C++? 09 What is the difference between shallow copy and deep copy? 10 What are static members in C++? 11 What are the differences between struct and class in C++? 12 What is type casting in C++? 13 What are abstract classes and interfaces in C++? 14 What is std::string and common string operations? 15 What are function pointers and std::function in C++? 16 What are design patterns commonly used in C++?

01 What is undefined behavior in C++ and how do you avoid it? 02 What is template metaprogramming in C++? 03 What are C++20 features? 04 What is memory alignment and padding in C++? 05 What is the C++ memory model and atomic operations? 06 What are C++ optimization techniques? 07 What is Variadic Templates and Parameter Packs? 08 What is the PIMPL idiom in C++?