Top 30 Most Common cpp interview questions You Should Prepare For

Landing a job as a C++ developer requires more than just coding skills. You need to confidently articulate your knowledge and problem-solving abilities during interviews. Mastering commonly asked cpp interview questions is crucial for boosting your confidence, providing clarity in your responses, and ultimately enhancing your overall interview performance. Preparation is key, and this guide will arm you with the knowledge you need to succeed. Verve AI’s Interview Copilot is your smartest prep partner—offering mock interviews tailored to C++ roles. Start for free at Verve AI.

What are cpp interview questions?

cpp interview questions are designed to assess a candidate's proficiency in the C++ programming language, their understanding of core concepts, and their ability to apply these concepts to solve real-world problems. These questions typically cover a wide range of topics including object-oriented programming (OOP) principles, memory management, data structures, algorithms, and the C++ Standard Template Library (STL). The goal of these cpp interview questions is to determine if the candidate possesses the necessary skills and knowledge to contribute effectively to a C++ development team. Experienced developers can expect more in-depth cpp interview questions focusing on design patterns, system architecture, and performance optimization.

Why do interviewers ask cpp interview questions?

Interviewers ask cpp interview questions to gauge a candidate's technical skills and problem-solving capabilities. By exploring topics such as inheritance, polymorphism, memory management, and templates, interviewers can assess a candidate's understanding of C++ fundamentals and their ability to write efficient and maintainable code. Additionally, cpp interview questions help interviewers determine if a candidate has practical experience applying their knowledge in real-world scenarios. Interviewers also look for a candidate's ability to think critically, communicate clearly, and approach challenges systematically. Ultimately, cpp interview questions are used to evaluate whether a candidate possesses the technical expertise and problem-solving skills necessary to excel in a C++ development role.

List Preview:

Here's a quick preview of the 30 cpp interview questions we'll be covering:

1. What are the differences between C and C++?

2. What is inheritance in C++?

3. What are static members and static member functions?

4. What is a namespace in C++?

5. What is operator overloading?

6. What is polymorphism?

7. What is the difference between a pointer and a reference?

8. Explain the concept of virtual functions.

9. What are smart pointers?

10. What is the difference between new and malloc?

11. What is the RAII principle?

12. What is a template in C++?

13. What is the difference between struct and class in C++?

14. What is the Standard Template Library (STL)?

15. What is the significance of the const keyword?

16. What are friend functions and friend classes?

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

18. What is exception handling in C++?

19. What are lvalues and rvalues?

20. Explain move semantics.

21. What is the difference between virtual, override, and final?

22. How does multiple inheritance work?

23. What are pure virtual functions and abstract classes?

24. What is the rule of three/five/zero?

25. What is inline function?

26. What is the difference between stack and heap memory?

27. What is a lambda expression?

28. What is the difference between throw and noexcept?

29. What are move constructors and move assignment operators?

30. How to prevent memory leaks in C++?

## 1. What are the differences between C and C++?

Why you might get asked this:

This is a fundamental question that assesses your understanding of the core distinctions between the two languages. Interviewers want to know if you grasp the shift from procedural to object-oriented programming and how C++ extends C’s capabilities. It tests your foundational knowledge in differentiating the feature sets of C and C++ programming languages and how they approach software design, a key aspect in cpp interview questions.

How to answer:

Start by highlighting that C is primarily a procedural language, whereas C++ is a hybrid language supporting both procedural and object-oriented paradigms. Then, elaborate on C++'s support for classes, inheritance, polymorphism, and other OOP features absent in C. Mention stronger type checking, exception handling, function overloading, and templates as other key differences. Frame your answer by emphasizing how these features in C++ enable more complex and maintainable software development.

Example answer:

"C is a procedural language focused on structured programming, while C++ builds upon C by adding object-oriented features. So, while you can write C-style code in C++, it also supports classes, inheritance, and polymorphism, allowing for more complex and modular designs. For example, I used inheritance in a project to create a hierarchy of game objects, which would have been much more cumbersome in C. This difference highlights how C++ goes beyond C in supporting modern software development practices."

## 2. What is inheritance in C++?

Why you might get asked this:

Inheritance is a cornerstone of object-oriented programming. Interviewers want to assess your understanding of how it promotes code reuse, establishes relationships between classes, and enables polymorphism. Grasping inheritance is crucial for designing robust and scalable applications. It's a classic topic for cpp interview questions because it's central to object-oriented design.

How to answer:

Explain that inheritance allows a class (derived class) to inherit properties and behaviors (data members and member functions) from another class (base class). Emphasize that this promotes code reuse, avoids redundancy, and facilitates polymorphism. Illustrate with a simple example, such as a 'Vehicle' base class and 'Car' or 'Truck' derived classes, to demonstrate the concept.

Example answer:

"Inheritance is a mechanism where a new class, called the derived class, inherits attributes and methods from an existing class, known as the base class. This allows you to reuse code and create a hierarchy of classes. In a recent project, I used inheritance to create different types of user roles, each inheriting common properties from a base 'User' class but adding specific permissions. This made the code more organized and easier to maintain."

## 3. What are static members and static member functions?

Why you might get asked this:

This question checks your understanding of class-level data and functions, as opposed to instance-specific ones. Static members are essential for sharing data across all instances of a class, and static member functions provide a way to operate on this shared data. It’s a common element in cpp interview questions, testing your depth of knowledge of class structure.

How to answer:

Explain that static members belong to the class itself, not to any particular object of the class. There is only one copy of a static member shared by all objects. Also, static member functions can only access static data members and can be called without creating an object of the class. Provide a usage example, such as counting the number of instances created for a class.

Example answer:

"Static members are variables that belong to the class itself rather than any specific instance. This means there's only one copy shared by all objects of the class. Static member functions can access only these static members and can be called directly using the class name, without needing an object. For example, in a logging system, I used a static counter to keep track of the total number of log entries across all instances."

## 4. What is a namespace in C++?

Why you might get asked this:

Namespaces are crucial for organizing code and preventing naming conflicts, especially in large projects or when using multiple libraries. This question assesses your understanding of how to manage code organization and avoid collisions. cpp interview questions often include namespaces due to their importance in managing code complexity.

How to answer:

Define a namespace as a declarative region that provides a scope to identifiers (types, functions, variables). Explain that namespaces are used to avoid name collisions, particularly in large projects or when integrating multiple libraries. Emphasize that you can access members of a namespace using the scope resolution operator (::).

Example answer:

"A namespace is like a container that holds a set of identifiers, such as variables, functions, and classes, under a specific name. It's used to avoid naming conflicts, especially when you're working with multiple libraries or a large codebase. For example, in a recent project, we used namespaces to separate different modules of the application, ensuring that functions with the same name in different modules didn't collide."

## 5. What is operator overloading?

Why you might get asked this:

Operator overloading allows you to define the behavior of operators for user-defined types. This question checks your understanding of how to extend the functionality of operators to work with custom classes, enhancing code readability and expressiveness. Understanding operator overloading is tested in cpp interview questions to assess your ability to customize language features.

How to answer:

Explain that operator overloading allows you to redefine the behavior of operators (+, -, *, etc.) for user-defined types (classes). Mention that this enables you to perform operations that are meaningful to the class objects, making the code more intuitive and easier to read. Provide an example, such as overloading the '+' operator to add two objects of a custom 'Vector' class.

Example answer:

"Operator overloading lets you redefine how operators like '+', '-', or '*' behave when used with objects of your own classes. This allows you to write more intuitive code. For instance, I overloaded the '+' operator for a 'ComplexNumber' class so that it could directly add two complex numbers together using the '+' symbol, making the code much cleaner than using a separate 'add' function."

## 6. What is polymorphism?

Why you might get asked this:

Polymorphism is a fundamental concept in object-oriented programming. Interviewers want to assess your understanding of how it allows objects of different classes to be treated through a common interface, enabling dynamic method binding at runtime. It is one of the key concepts for cpp interview questions.

How to answer:

Explain that polymorphism allows treating objects of different classes through a common interface, mainly achieved via virtual functions and inheritance. Emphasize that this enables dynamic method binding at runtime, allowing the correct method to be called based on the actual object type. Provide an example, such as a 'Shape' base class with 'Circle' and 'Square' derived classes, where a virtual 'draw' function is implemented differently in each derived class.

Example answer:

"Polymorphism means 'many forms,' and in C++, it allows you to treat objects of different classes in a uniform way. This is typically achieved through inheritance and virtual functions. For example, if you have a base class 'Animal' with a virtual function 'makeSound,' different derived classes like 'Dog' and 'Cat' can override this function to produce different sounds. This lets you call 'makeSound' on a collection of 'Animal' objects, and the correct sound will be made based on the actual object type."

## 7. What is the difference between a pointer and a reference?

Why you might get asked this:

This question tests your understanding of fundamental C++ concepts related to memory management and object manipulation. Interviewers want to know if you understand how pointers and references work, their differences, and when to use each one appropriately. Often a part of cpp interview questions, pointers and references are essential to understanding how memory is handled.

How to answer:

Explain that a pointer stores an address and can be reassigned or set to null. In contrast, a reference is an alias for another variable, must be initialized upon declaration, and cannot be null or reseated. Emphasize that pointers require dereferencing to access the value, while references do not.

Example answer:

"A pointer holds the memory address of a variable and can be reassigned to point to different variables, or even be null. A reference, on the other hand, is an alias for an existing variable and must be initialized when it's declared. Once initialized, a reference cannot be changed to refer to a different variable. Pointers require you to dereference them to access the value they point to, while references do not. I often use pointers when I need to manipulate memory addresses directly or when dealing with dynamic memory allocation."

## 8. Explain the concept of virtual functions.

Why you might get asked this:

Virtual functions are central to achieving polymorphism in C++. This question assesses your understanding of dynamic dispatch and how virtual functions enable runtime polymorphism, allowing derived classes to override base class behavior. It is a common concept to address when discussing cpp interview questions, particularly those related to object-oriented programming.

How to answer:

Explain that a virtual function is a member function in a base class that you expect to be overridden in derived classes. Mention that declaring a function as virtual enables runtime polymorphism, where the correct version of the function to call is determined at runtime based on the actual object type. Use the example of a 'Shape' class with a virtual 'draw' function, overridden in 'Circle' and 'Square' classes.

Example answer:

"A virtual function is a member function declared in a base class that you expect to be redefined in derived classes. When you call a virtual function through a base class pointer or reference, the actual function that gets executed is determined at runtime based on the type of object being pointed to. This is crucial for achieving polymorphism. For instance, if I have a base class 'Shape' with a virtual 'draw' function, derived classes like 'Circle' and 'Square' can provide their own implementations, allowing me to draw different shapes using a single 'Shape' pointer."

## 9. What are smart pointers?

Why you might get asked this:

Smart pointers are essential for managing dynamic memory in C++ and preventing memory leaks. Interviewers want to know if you understand how smart pointers work, the different types available, and their benefits over raw pointers. Important in cpp interview questions, especially those related to memory management, smart pointers are fundamental to writing safe code.

How to answer:

Explain that smart pointers (like std::uniqueptr, std::sharedptr) manage dynamic memory automatically, ensuring proper deallocation and preventing memory leaks. Describe the different types of smart pointers and their use cases: uniqueptr for exclusive ownership, sharedptr for shared ownership, and weak_ptr for non-owning observers.

Example answer:

"Smart pointers are classes that act like pointers but automatically manage the memory they point to, preventing memory leaks. uniqueptr provides exclusive ownership, ensuring that only one smart pointer points to a given object. sharedptr allows multiple smart pointers to point to the same object, with the object being deleted when the last sharedptr is destroyed. weakptr provides a non-owning reference to an object managed by sharedptr. In my projects, I primarily use uniqueptr for single ownership and shared_ptr when multiple parts of the code need to share ownership of an object."

## 10. What is the difference between new and malloc?

Why you might get asked this:

This question tests your understanding of memory allocation in C++ and the differences between C-style memory management (malloc) and C++-style memory management (new). Interviewers want to assess your knowledge of object construction and destruction, as well as type safety. A standard question for cpp interview questions, knowing the difference between new and malloc shows you understand the language's core memory allocation principles.

How to answer:

Explain that new constructs objects and calls constructors, returning a typed pointer, while malloc allocates raw memory but does not call constructors and returns a void *. Emphasize that new is type-safe, whereas malloc requires explicit casting. Also, new and delete should be used together, and malloc and free should be used together to avoid memory corruption.

Example answer:

"new is a C++ operator that allocates memory and also calls the constructor of the object being created. It returns a pointer of the correct type. malloc, on the other hand, is a C function that allocates a block of raw, uninitialized memory and returns a void*, which you then need to cast to the correct type. new is type-safe and handles object construction, while malloc only allocates memory. I always prefer using new in C++ because it ensures that objects are properly initialized."

## 11. What is the RAII principle?

Why you might get asked this:

Resource Acquisition Is Initialization (RAII) is a fundamental C++ programming idiom for managing resources. Interviewers want to assess your understanding of how RAII ensures automatic resource release and prevents resource leaks, making your code more robust and reliable. It's a key principle in cpp interview questions focused on memory management.

How to answer:

Explain that RAII binds resource lifecycle to object lifetime, ensuring automatic release of resources like memory or file handles. The resource is acquired during object construction and released during object destruction. Emphasize that this prevents resource leaks and simplifies resource management.

Example answer:

"RAII, or Resource Acquisition Is Initialization, is a C++ technique where you tie the lifecycle of a resource to the lifetime of an object. When the object is created, it acquires the resource, and when the object is destroyed, it automatically releases the resource. This ensures that resources are always properly released, even if exceptions are thrown. For example, I use RAII when working with file streams, ensuring that the file is automatically closed when the stream object goes out of scope."

## 12. What is a template in C++?

Why you might get asked this:

Templates enable generic programming in C++, allowing you to write code that works with different data types without being rewritten for each type. Interviewers want to assess your understanding of how templates promote code reuse and flexibility. cpp interview questions often cover templates due to their importance in generic programming.

How to answer:

Explain that templates enable generic programming by allowing functions and classes to operate with generic types, defined at compile time. Mention that templates can be used to create functions or classes that work with different data types without having to write separate code for each type. Provide an example, such as a template function to sort an array of any data type.

Example answer:

"Templates in C++ allow you to write code that works with any data type without having to write separate code for each type. They enable generic programming by defining functions or classes that operate on generic types, which are specified at compile time. For example, I've used templates to create a generic sorting function that can sort arrays of integers, floats, or any other comparable type. This significantly reduces code duplication and makes the code more maintainable."

## 13. What is the difference between struct and class in C++?

Why you might get asked this:

This question checks your understanding of the subtle differences between struct and class in C++. Interviewers want to know if you are aware of the default access specifiers and how they impact encapsulation and data hiding. This distinction is crucial in answering cpp interview questions related to object-oriented design.

How to answer:

Explain that, by default, members of a struct are public, while members of a class are private. Emphasize that this is the only difference between them and that both can have member functions, inheritance, and other OOP features.

Example answer:

"The main difference between a struct and a class in C++ is the default access specifier. In a struct, members are public by default, while in a class, members are private by default. Other than that, they are essentially the same; both can have member functions, inheritance, and other object-oriented features. I typically use struct for simple data structures where I want the members to be publicly accessible, and class for more complex objects where I want to enforce encapsulation."

## 14. What is the Standard Template Library (STL)?

Why you might get asked this:

The STL is a powerful library that provides a set of generic classes and functions for common programming tasks. Interviewers want to assess your familiarity with the STL and its components, as well as your ability to use it effectively in your code. Knowledge of STL is frequently tested in cpp interview questions due to its importance in modern C++ development.

How to answer:

Explain that the STL is a powerful C++ library providing common data structures (vector, list, map) and algorithms (sort, search). Mention that it includes containers, iterators, algorithms, and function objects, all designed to work together seamlessly. Provide examples of how you have used STL containers and algorithms in your projects.

Example answer:

"The Standard Template Library, or STL, is a collection of template classes and functions that provide common data structures and algorithms. It includes containers like vector, list, map, and algorithms like sort, search, and transform. I've used the STL extensively in my projects. For example, I've used std::vector for dynamic arrays, std::map for key-value storage, and std::sort for sorting data efficiently. The STL makes C++ development faster and more efficient."

## 15. What is the significance of the const keyword?

Why you might get asked this:

The const keyword is used to specify that a variable or function cannot modify certain data. Interviewers want to assess your understanding of how const helps enforce immutability, improve code safety, and optimize performance. One of the fundamental topics in cpp interview questions, understanding the use of const is critical to writing robust code.

How to answer:

Explain that const makes variables immutable, enforces read-only access to functions, and helps prevent accidental modifications. Mention that const can be used with variables, pointers, function parameters, and member functions. Emphasize that using const improves code safety and allows the compiler to perform optimizations.

Example answer:

"const is a keyword that signifies that a value should not be modified after initialization. It can be applied to variables, pointers, function parameters, and member functions. When applied to a variable, it makes the variable read-only. When applied to a function parameter, it prevents the function from modifying the parameter. When applied to a member function, it indicates that the function does not modify the object's state. I use const extensively to make my code safer and more predictable."

## 16. What are friend functions and friend classes?

Why you might get asked this:

Friend functions and friend classes are used to grant access to private and protected members of a class. Interviewers want to assess your understanding of how friends can be used to break encapsulation and the trade-offs involved. cpp interview questions often address friend functions to see if you understand access modifiers and how to bypass them.

How to answer:

Explain that friend functions or classes can access private and protected members of the class where they are declared as friends. Mention that friends can be useful in certain situations, such as when implementing operator overloading or when working with closely related classes. Emphasize that friends should be used sparingly, as they can weaken encapsulation.

Example answer:

"Friend functions and friend classes are mechanisms that allow a function or another class to access the private and protected members of a class. A friend function is not a member of the class, but it is granted access to the class's internals. A friend class can access the private and protected members of another class. I use friend functions and classes sparingly because they can weaken encapsulation, but they can be useful in certain situations, such as when implementing operator overloading or when two classes are tightly coupled."

## 17. What is the difference between shallow copy and deep copy?

Why you might get asked this:

This question tests your understanding of how objects are copied in C++ and the implications of copying objects that contain pointers. Interviewers want to know if you understand the difference between copying the pointer itself (shallow copy) and copying the data that the pointer points to (deep copy). Important for memory management, deep vs shallow copy often appears in cpp interview questions.

How to answer:

Explain that a shallow copy copies object member values as is, including pointers, while a deep copy duplicates pointed-to data, ensuring separate copies. Emphasize that shallow copies can lead to issues such as dangling pointers and double deletion, while deep copies avoid these issues but can be more expensive.

Example answer:

"A shallow copy creates a new object and then copies the values of the original object's members to the new object. If the object contains pointers, the pointers are copied, but the data they point to is not. This means that both objects will point to the same data. A deep copy, on the other hand, creates a new object and then copies the values of the original object's members to the new object. If the object contains pointers, the data they point to is also copied, creating a completely independent copy. I prefer deep copies when I need to ensure that the objects are truly independent, but I'm mindful of the performance overhead."

## 18. What is exception handling in C++?

Why you might get asked this:

Exception handling is a mechanism for dealing with runtime errors in a robust and controlled manner. Interviewers want to assess your understanding of how exceptions are thrown, caught, and handled, and how they can be used to improve code reliability. cpp interview questions related to error handling are key to understanding how you handle unexpected situations in your code.

How to answer:

Explain that C++ uses try, catch, and throw blocks to handle runtime errors gracefully. Mention that the try block encloses the code that might throw an exception, the catch block catches and handles the exception, and the throw statement throws the exception. Emphasize that exception handling helps prevent program crashes and allows for more graceful error recovery.

Example answer:

"Exception handling in C++ provides a way to handle runtime errors in a structured and controlled manner. You use try, catch, and throw blocks. Code that might throw an exception is placed inside a try block. If an exception occurs, the program jumps to the catch block, which handles the exception. The throw statement is used to throw an exception. I use exception handling to make my code more robust and prevent crashes due to unexpected errors."

## 19. What are lvalues and rvalues?

Why you might get asked this:

This question tests your understanding of value categories in C++, which are important for understanding move semantics and rvalue references. Interviewers want to know if you can distinguish between lvalues and rvalues and how they are used in different contexts. It’s often asked in cpp interview questions focusing on advanced language features.

How to answer:

Explain that an lvalue is an object that occupies identifiable memory (can appear on the left side of assignment), while an rvalue is a temporary value or literal (usually on the right side). Mention that lvalues have names and addresses, while rvalues are typically unnamed temporary objects.

Example answer:

"An lvalue is an expression that refers to a memory location and can appear on the left-hand side of an assignment. It has a name and an address. An rvalue, on the other hand, is a temporary value that does not persist beyond the expression in which it is used. It typically appears on the right-hand side of an assignment. Understanding the distinction between lvalues and rvalues is crucial for understanding move semantics and rvalue references."

## 20. Explain move semantics.

Why you might get asked this:

Move semantics are a performance optimization technique that avoids unnecessary copying of data. Interviewers want to assess your understanding of how move semantics work and how they can be used to improve the efficiency of your code. It is relevant to cpp interview questions that touch on performance optimization.

How to answer:

Explain that move semantics optimize resource transfer from temporary objects (rvalues) to avoid expensive deep copies using move constructors and move assignment. Mention that move semantics are particularly useful when dealing with large objects or objects that own resources.

Example answer:

"Move semantics is a performance optimization technique that allows you to transfer the ownership of resources from one object to another, rather than copying them. This is particularly useful when dealing with temporary objects, as it avoids the overhead of deep copying. Move semantics are implemented using move constructors and move assignment operators, which take rvalue references as their parameters. I use move semantics to improve the performance of my code, especially when working with large objects or objects that own resources."

## 21. What is the difference between virtual, override, and final?

Why you might get asked this:

These keywords are used to control inheritance and polymorphism in C++. Interviewers want to assess your understanding of how these keywords affect the behavior of virtual functions and how they can be used to prevent unintended overriding or inheritance. The proper use of virtual, override, and final are key components in cpp interview questions that focus on inheritance.

How to answer:

Explain that virtual marks a method for dynamic dispatch, override indicates a method overrides a base class virtual method, and final prevents further overriding. Mention that override helps catch errors at compile time if a virtual function is not correctly overridden, and final can be used to prevent unintended inheritance or overriding.

Example answer:

"virtual is used to declare a virtual function in a base class, which means that derived classes can override the function's behavior. override is used in a derived class to explicitly indicate that a function is intended to override a virtual function in the base class. This helps catch errors at compile time if the function signature doesn't match. final is used to prevent a virtual function from being overridden in any further derived classes, or to prevent a class from being inherited from."

## 22. How does multiple inheritance work?

Why you might get asked this:

Multiple inheritance allows a class to inherit from multiple base classes. Interviewers want to assess your understanding of how multiple inheritance works, the challenges it presents (such as the diamond problem), and how to resolve those challenges using virtual inheritance. This topic comes up in cpp interview questions when assessing your knowledge of complex inheritance scenarios.

How to answer:

Explain that a class can inherit from more than one base class, combining their interfaces. Mention that C++ resolves ambiguity using virtual inheritance to avoid duplication, particularly in the case of the diamond problem.

Example answer:

"Multiple inheritance allows a class to inherit from multiple base classes, combining their interfaces. However, it can lead to the 'diamond problem,' where a class inherits from two classes that both inherit from a common base class, resulting in multiple copies of the base class's members. C++ resolves this ambiguity using virtual inheritance, which ensures that only one copy of the base class is inherited. I use multiple inheritance sparingly and prefer composition when possible, as it can lead to more maintainable code."

## 23. What are pure virtual functions and abstract classes?

Why you might get asked this:

Pure virtual functions and abstract classes are used to define interfaces and enforce a certain structure in derived classes. Interviewers want to assess your understanding of how they work and how they can be used to create flexible and extensible code. An understanding of pure virtual functions and abstract classes is often needed in cpp interview questions to assess your grasp of interface design.

How to answer:

Explain that pure virtual functions have no implementation (=0) and make a class abstract. Abstract classes cannot be instantiated. Mention that derived classes must implement pure virtual functions to become concrete (non-abstract).

Example answer:

"A pure virtual function is a virtual function that has no implementation in the base class. It is declared with = 0. A class that contains one or more pure virtual functions is called an abstract class. Abstract classes cannot be instantiated directly; they must be subclassed, and the pure virtual functions must be overridden in the derived class before it can be instantiated. I use abstract classes to define interfaces and enforce a certain structure in derived classes."

## 24. What is the rule of three/five/zero?

Why you might get asked this:

This question tests your understanding of resource management and object lifecycle in C++. Interviewers want to know if you are familiar with the guidelines for defining or deleting special member functions (destructor, copy constructor, copy assignment operator, move constructor, move assignment operator) to ensure proper resource handling. This is a very important topic for cpp interview questions focused on correct object management.

How to answer:

Explain that the rule of three states that if you define a destructor, copy constructor, or copy assignment operator, you should define all three. The rule of five extends this to include move constructor and move assignment operator in C++11. The rule of zero suggests preferring RAII and no manual resource management.

Example answer:

"The rule of three states that if a class requires a custom destructor, copy constructor, or copy assignment operator, it likely requires all three. The rule of five extends this to include the move constructor and move assignment operator, which are important for move semantics. The rule of zero advocates for using RAII principles and avoiding manual resource management altogether. I generally follow the rule of zero by using smart pointers and other RAII techniques to manage resources automatically."

## 25. What is inline function?

Why you might get asked this:

Inline functions are used to optimize performance by reducing function call overhead. Interviewers want to assess your understanding of how inline functions work and when they should be used. One of the performance considerations in cpp interview questions is the use of inline functions to improve efficiency.

How to answer:

Explain that an inline function suggests the compiler to insert the function code at the point of call to reduce function call overhead. Mention that inline functions are typically small and frequently called and that the compiler may choose to ignore the inline suggestion.

Example answer:

"An inline function is a function that the compiler attempts to expand inline at the point where it is called, rather than performing a function call. This can reduce function call overhead, but it can also increase code size. I typically use inline functions for small, frequently called functions where performance is critical."

## 26. What is the difference between stack and heap memory?

Why you might get asked this:

This question tests your understanding of memory management in C++. Interviewers want to know if you can distinguish between stack and heap memory, their characteristics, and when to use each one. Understanding the memory model is foundational in cpp interview questions.

How to answer:

Explain that the stack is for static memory allocation, automatic variables, with limited size, while the heap is for dynamic memory allocation with manual control over lifetime. Mention that stack memory is automatically managed, while heap memory requires manual allocation and deallocation.

Example answer:

"Stack memory is used for static memory allocation and is automatically managed by the compiler. It is typically used for local variables and function call information. Heap memory, on the other hand, is used for dynamic memory allocation and requires manual management. You allocate memory on the heap using new and deallocate it using delete. Stack memory is faster but has limited size, while heap memory is more flexible but requires careful management to avoid memory leaks."

## 27. What is a lambda expression?

Why you might get asked this:

Lambda expressions are a concise way to create anonymous functions in C++. Interviewers want to assess your understanding of how lambda expressions work and how they can be used to simplify code and improve readability. Increasingly common in modern C++, lambda expressions are frequently tested in cpp interview questions.

How to answer:

Explain that lambdas are anonymous functions defined inline, often used for callbacks or STL algorithms. Mention that lambdas can capture variables from their surrounding scope and that they can be used to create function objects on the fly.

Example answer:

"A lambda expression is a concise way to create an anonymous function in C++. It allows you to define a function inline, without having to give it a name. Lambda expressions are often used for callbacks or with STL algorithms. They can capture variables from their surrounding scope, which can be very useful for creating function objects on the fly. I find lambda expressions to be a powerful tool for simplifying code and improving readability."

## 28. What is the difference between throw and noexcept?

Why you might get asked this:

These keywords are used to specify how a function handles exceptions. Interviewers want to assess your understanding of how throw and noexcept affect exception handling and code optimization. Error handling with throw and noexcept is a critical aspect of cpp interview questions.

How to answer:

Explain that throw specifies exceptions a function can emit, while noexcept declares a function that does not throw exceptions, enabling optimizations. Mention that noexcept functions can improve performance because the compiler can make assumptions about exception handling.

Example answer:

"throw is used to specify the types of exceptions that a function