Top 30 Most Common C++ Coding Interview Questions You Should Prepare For

Landing a job in C++ development requires more than just technical skills; it demands a solid understanding of core C++ concepts and the ability to articulate them clearly. Preparing for c++ coding interview questions is crucial. It not only builds your confidence but also ensures you can effectively demonstrate your expertise during the interview process. Mastering these commonly asked c++ coding interview questions can significantly impact your overall performance.

What are c++ coding interview questions?

C++ coding interview questions are designed to assess a candidate's proficiency in the C++ programming language. These questions span a wide range of topics, including fundamental programming concepts, object-oriented programming (OOP) principles, memory management, data structures, and algorithm design. The purpose of these c++ coding interview questions is to evaluate not only your theoretical knowledge but also your problem-solving abilities and practical experience in C++ development. A good understanding of these questions and their answers will definitely help you in your interviews.

Why do interviewers ask c++ coding interview questions?

Interviewers ask c++ coding interview questions to determine if a candidate possesses the necessary skills and understanding to succeed in a C++ development role. They aim to assess several key areas, including:

• Technical Knowledge: Evaluating your understanding of C++ syntax, semantics, and the standard library.

• Problem-Solving Ability: Assessing your ability to analyze problems, devise solutions, and implement them using C++.

• Practical Experience: Gauging your hands-on experience with C++ development, including project experience and familiarity with common C++ development tools and techniques.

• Communication Skills: Observing how clearly and concisely you can explain complex technical concepts.

By posing c++ coding interview questions, interviewers gain insights into your overall competence and suitability for the position.

List Preview:

Here's a preview of the 30 most common c++ coding interview questions we'll cover:

1. How to check whether a number is positive or negative in C++?

2. How to find the greatest of three numbers?

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

4. Explain inheritance in C++.

5. What are static members in C++?

6. What is a pointer and which operations are permitted on pointers?

7. What is the purpose of the delete operator?

8. What is an overflow error?

9. What does the scope resolution operator :: do?

10. What are C++ access modifiers?

11. Can you compile a program without main() in C++?

12. What is an abstract class?

13. Explain the difference between ++a and a++.

14. What are virtual functions?

15. Explain the concept of pointers to pointers.

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

17. What is the Rule of Three in C++?

18. Explain function overloading and operator overloading.

19. What is RAII (Resource Acquisition Is Initialization)?

20. What are templates in C++?

21. What is the use of mutable keyword?

22. What is the difference between new and malloc()?

23. Explain stack vs heap memory.

24. What is a smart pointer?

25. What is an iterator?

26. Explain difference between const pointer and pointer to const.

27. What is a lambda expression?

28. What is a dangling pointer?

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

30. How do you prevent a class from being inherited?

## 1. How to check whether a number is positive or negative in C++?

Why you might get asked this:

This question assesses your understanding of basic conditional statements and logical operators in C++. Interviewers want to see if you can write simple, clean code to solve a fundamental problem. This type of c++ coding interview questions checks your basic syntax knowledge.

How to answer:

Start by explaining the general approach of using an if-else statement. Mention that you'll check if the number is greater than or equal to zero. If it is, the number is positive (or zero); otherwise, it's negative. Briefly discuss edge cases if prompted.

Example answer:

"The most straightforward way to check if a number is positive or negative is to use a simple if-else statement. I'd check if the number is greater than or equal to zero. If that's true, it's positive or zero. Otherwise, it's negative. In a real-world scenario, I might add additional checks for non-numeric input, but for this basic check, if-else is perfectly sufficient. This shows I can quickly apply fundamental logic in C++."

## 2. How to find the greatest of three numbers?

Why you might get asked this:

This question evaluates your ability to apply conditional logic and potentially use ternary operators or standard library functions for comparison. It also tests your problem-solving skills in a simple scenario. Success with c++ coding interview questions depends on clear logic.

How to answer:

Describe your approach, mentioning options like using nested if-else statements or the std::max function (if applicable and allowed). Explain the logic behind each approach and any trade-offs involved. Briefly mention how this extends to finding the maximum of more numbers.

Example answer:

"There are a couple of ways to find the greatest of three numbers. I could use nested if-else statements to compare them pairwise. Alternatively, if permitted, I'd prefer using the std::max function, which might be more concise. For example, I could compare the first two numbers, then compare the result with the third. Using std::max generally leads to cleaner and more readable code, which is something I always aim for. This shows I can choose appropriate tools and maintain code clarity."

## 3. What is the difference between C and C++?

Why you might get asked this:

This question assesses your understanding of the fundamental differences between the two languages, particularly regarding programming paradigms and features. Interviewers want to see if you grasp the core concepts of object-oriented programming (OOP) supported by C++. This is a common type of c++ coding interview questions.

How to answer:

Explain that C is primarily a procedural programming language, while C++ supports both procedural and object-oriented paradigms. Highlight key OOP features in C++, such as classes, inheritance, polymorphism, and encapsulation. Also, briefly mention other differences like memory management and standard library features.

Example answer:

"The main difference lies in their programming paradigms. C is primarily a procedural language, focusing on functions and step-by-step execution. C++, on the other hand, builds upon C by adding object-oriented features like classes, inheritance, and polymorphism. So, while you can write procedural code in C++, it also enables you to create more modular and reusable code through OOP. This difference makes C++ better suited for larger, more complex projects, in my opinion."

## 4. Explain inheritance in C++.

Why you might get asked this:

Inheritance is a core OOP concept. This question evaluates your understanding of how classes can inherit properties and behaviors from other classes, promoting code reuse and creating hierarchical relationships. Understanding inheritance is key to answering c++ coding interview questions related to OOP.

How to answer:

Define inheritance as a mechanism where a class (derived class) inherits properties and methods from another class (base class). Explain the benefits of code reuse and creating hierarchical relationships. You can also touch upon different types of inheritance (single, multiple, etc.).

Example answer:

"Inheritance is a fundamental concept in OOP that allows a class to inherit properties and behaviors from another class. The class that inherits is called the 'derived class,' and the class it inherits from is the 'base class.' This promotes code reuse because you don't have to rewrite the same code in multiple classes. For example, I worked on a project where we had a 'Vehicle' base class, and then derived classes like 'Car' and 'Truck' inherited common attributes like speed and engine size, which saved us a lot of development time."

## 5. What are static members in C++?

Why you might get asked this:

This question tests your understanding of static variables and methods within a class. Interviewers want to see if you know how static members differ from instance members and their use cases. Such understanding is essential when answering c++ coding interview questions.

How to answer:

Explain that static members belong to the class itself rather than to any specific object instance. Mention that there's only one copy of a static member shared by all objects of the class. Describe common use cases like counters or shared resources.

Example answer:

"Static members are unique because they belong to the class itself, not to any particular instance of the class. This means there's only one copy of a static member, shared by all objects. I used this in a project where we needed to keep track of the total number of objects created for a certain class. A static counter was perfect for that – it gets incremented in the constructor and keeps a running total across all instances. It's really useful for global state management within a class."

## 6. What is a pointer and which operations are permitted on pointers?

Why you might get asked this:

Pointers are a powerful but potentially dangerous feature in C++. This question assesses your understanding of how pointers work, their purpose, and the operations that can be performed on them. Mastering pointers is crucial for answering advanced c++ coding interview questions.

How to answer:

Define a pointer as a variable that stores the memory address of another variable. List the permitted operations: dereferencing (*), pointer arithmetic (++, --, +, -), comparison, and assignment. Explain the risks associated with pointer arithmetic, such as accessing invalid memory locations.

Example answer:

"A pointer is essentially a variable that holds the memory address of another variable. You can do several things with pointers. You can dereference them with the * operator to access the value at that address. You can also perform arithmetic, like incrementing or decrementing the pointer to move through memory. You can also compare pointers to see if they point to the same location, and assign one pointer's value to another. In my experience, you need to be really careful with pointer arithmetic to avoid accessing invalid memory, which can lead to crashes."

## 7. What is the purpose of the delete operator?

Why you might get asked this:

This question checks your understanding of dynamic memory management in C++. Interviewers want to ensure you know how to properly deallocate memory to prevent memory leaks. Being able to discuss memory management is essential for c++ coding interview questions.

How to answer:

Explain that the delete operator is used to deallocate memory that was previously allocated using the new operator. Emphasize the importance of using delete to prevent memory leaks, especially in long-running applications. Explain delete[] for array allocation with new[].

Example answer:

"The delete operator is critical for managing dynamic memory in C++. When you allocate memory using new, that memory stays allocated until you explicitly release it using delete. Failing to do so results in a memory leak, where your program gradually consumes more and more memory over time. So, delete is used to free up that memory and return it to the system. I remember one project where we had a serious memory leak because we forgot to use delete on some dynamically allocated objects, which caused the application to crash after running for a few hours."

## 8. What is an overflow error?

Why you might get asked this:

This question assesses your understanding of the limitations of data types and the potential for unexpected behavior when values exceed those limits. This demonstrates an understanding of potential pitfalls when answering c++ coding interview questions.

How to answer:

Explain that an overflow error occurs when a value exceeds the storage capacity of its data type, causing it to "wrap around" to the minimum value (or vice versa for underflow). Provide an example, such as exceeding the maximum value of an int.

Example answer:

"An overflow error happens when you try to store a value in a variable that's larger than the maximum value that data type can hold. It's like trying to pour too much water into a glass – it spills over. For example, if an int can store a maximum value of, say, 2 billion, and you try to assign it 2.1 billion, it will wrap around to a negative number. I've seen this cause unexpected behavior in calculations, so it's important to be aware of the limits of your data types and handle potential overflows."

## 9. What does the scope resolution operator :: do?

Why you might get asked this:

This question checks your knowledge of a fundamental operator in C++ and its various uses. Interviewers want to see if you understand how to access members outside their immediate scope. Understanding this operator is key for more advanced c++ coding interview questions.

How to answer:

Explain the different uses of the scope resolution operator: accessing a global variable when a local variable has the same name, accessing a class member from outside the class, and defining a function outside of its class definition.

Example answer:

"The scope resolution operator (::) has several important uses in C++. First, it can be used to access a global variable when a local variable with the same name is in scope. Second, it's used to access static members of a class from outside the class. Finally, it's used to define a function outside of its class definition. For instance, if you have a function declared within a class but defined outside, you use :: to specify that the function belongs to that class."

## 10. What are C++ access modifiers?

Why you might get asked this:

This question tests your understanding of encapsulation and data hiding, key principles of object-oriented programming. Interviewers want to see if you understand how access modifiers control the visibility of class members. This is fundamental to many c++ coding interview questions.

How to answer:

List the three access modifiers: private, protected, and public. Explain the visibility rules for each modifier: private members are only accessible within the class; protected members are accessible within the class and its derived classes; public members are accessible from anywhere.

Example answer:

"C++ has three main access modifiers: private, protected, and public. Private members are only accessible from within the same class, which provides the highest level of data hiding. Protected members are accessible from within the class and any derived classes, allowing for inheritance-based access. Public members are accessible from anywhere, which is useful for defining the interface of your class. Using these modifiers helps enforce encapsulation and control how data is accessed and modified."

## 11. Can you compile a program without main() in C++?

Why you might get asked this:

This question tests your understanding of the compilation and linking process, as well as the role of the main() function as the entry point of execution. It addresses fundamental concepts that underpin answering more complex c++ coding interview questions.

How to answer:

Explain that a C++ program can be compiled without a main() function, but it cannot be executed as a standalone program. The main() function is the entry point where execution begins. You can compile code into a library or object file without main().

Example answer:

"Yes, you can definitely compile a C++ program without a main() function. However, the resulting compiled code won't be executable. The main() function is the entry point where the operating system starts running your program. If you don't have it, the compiler will create an object file or library. I've done this when creating libraries where I only need to compile the code but not run it directly. The final executable that uses the library will, of course, require a main() function."

## 12. What is an abstract class?

Why you might get asked this:

This question tests your knowledge of abstract classes and their role in defining interfaces and enforcing polymorphism. Interviewers want to see if you understand when and why to use abstract classes in your designs. Understanding inheritance and abstract classes are relevant to c++ coding interview questions about OOP.

How to answer:

Define an abstract class as a class that contains at least one pure virtual function (declared with = 0). Explain that abstract classes cannot be instantiated directly but can be used as base classes for other classes. Emphasize their role in defining a common interface for derived classes.

Example answer:

"An abstract class in C++ is a class that has at least one pure virtual function, which is a virtual function declared with = 0. Because of this pure virtual function, you can't create objects directly from an abstract class. Instead, you inherit from it and provide concrete implementations for the pure virtual functions in the derived classes. This is really useful for defining a common interface that all derived classes must implement. I've used abstract classes to design flexible systems where different components can be swapped out as long as they adhere to the interface defined by the abstract class."

## 13. Explain the difference between ++a and a++.

Why you might get asked this:

This question tests your understanding of pre-increment and post-increment operators, as well as their subtle differences in behavior and return values. This question can be used to filter out candidates struggling with basic c++ coding interview questions.

How to answer:

Explain that ++a is the pre-increment operator, which increments the value of a and then returns the incremented value. a++ is the post-increment operator, which returns the original value of a and then increments it. Emphasize the performance implications, where pre-increment can be more efficient for complex types.

Example answer:

"The difference between ++a and a++ is subtle but important. ++a is the pre-increment operator. It increments the value of a and then returns the incremented value. a++ is the post-increment operator. It returns the original value of a and then increments it. Also, I should point out that for simple types like int, there's not much of a performance difference, but for more complex types, ++a is often more efficient because it doesn't need to create a temporary copy of the original value."

## 14. What are virtual functions?

Why you might get asked this:

Virtual functions are a cornerstone of polymorphism in C++. This question assesses your understanding of dynamic dispatch and how virtual functions enable runtime polymorphism. This is one of the more common c++ coding interview questions on OOP.

How to answer:

Explain that virtual functions are functions declared with the virtual keyword in the base class. They allow derived classes to override the function's behavior, and the correct version of the function is called at runtime based on the actual object type (dynamic dispatch).

Example answer:

"Virtual functions are functions declared with the virtual keyword in a base class. The key thing about virtual functions is that they enable dynamic polymorphism, meaning that the specific function that gets called is determined at runtime based on the actual object type, not the declared type of the pointer or reference. This allows you to treat objects of different classes in a uniform way through a common base class interface, which is extremely powerful for building flexible and extensible systems."

## 15. Explain the concept of pointers to pointers.

Why you might get asked this:

This question tests your understanding of multiple levels of indirection and how pointers can be used to store the addresses of other pointers. It also hints to the interviewer that you can likely handle more difficult c++ coding interview questions on memory management.

How to answer:

Explain that a pointer to a pointer is a pointer variable that stores the memory address of another pointer variable. It allows you to indirectly access the value of the original variable through two levels of indirection. Describe scenarios where they are useful, such as manipulating arrays of pointers or implementing complex data structures.

Example answer:

"A pointer to a pointer is exactly what it sounds like: it's a pointer variable that stores the memory address of another pointer variable. So, instead of pointing directly to a value, it points to a location in memory that contains the address of the actual value. I've used these in scenarios where I need to modify a pointer itself within a function. Because C++ passes arguments by value by default, you'd need to pass a pointer to the pointer in order to change the original pointer's address."

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

Why you might get asked this:

This question assesses your understanding of how objects are copied and the potential issues that can arise when objects contain pointers to dynamically allocated memory. You are being assessed for memory management when answering c++ coding interview questions.

How to answer:

Explain that a shallow copy copies only the values of the object's member variables, including pointers. This means that the original and copied objects will point to the same dynamically allocated memory. A deep copy, on the other hand, allocates new memory for the copied object and copies the contents of the original object's dynamically allocated memory to the new memory.

Example answer:

"The difference between a shallow copy and a deep copy boils down to how they handle pointers to dynamically allocated memory. A shallow copy simply copies the pointer value, which means both the original and the copied object end up pointing to the same memory location. If one object modifies that memory, the other object is affected. A deep copy, on the other hand, creates a brand new block of memory and copies the data from the original object into that new memory. This way, each object has its own independent copy, preventing unintended side effects."

## 17. What is the Rule of Three in C++?

Why you might get asked this:

This question tests your awareness of the potential issues related to resource management and object copying in C++. It assesses your understanding of when and why to define custom copy constructors, assignment operators, and destructors. This helps to assess your competence in memory management when answering c++ coding interview questions.

How to answer:

Explain that the Rule of Three (now often referred to as the Rule of Five with the advent of move semantics in C++11) states that if a class requires a user-defined destructor, copy constructor, or copy assignment operator, it almost certainly requires all three. This is because these functions are often needed to properly manage dynamically allocated memory or other resources.

Example answer:

"The Rule of Three states that if a class needs a custom destructor, copy constructor, or copy assignment operator, it almost certainly needs all three. This is because if you're managing resources like dynamically allocated memory, the default implementations of these functions provided by the compiler might not do the right thing. For example, if you have a class that allocates memory in its constructor, you'll need a custom destructor to free that memory, a custom copy constructor to create a new copy of the data, and a custom copy assignment operator to avoid memory leaks when assigning one object to another."

## 18. Explain function overloading and operator overloading.

Why you might get asked this:

This question assesses your understanding of polymorphism and how it can be achieved through function and operator overloading. Interviewers want to see if you understand how to provide multiple implementations of a function or operator with different parameters. This is a common concept in c++ coding interview questions related to OOP.

How to answer:

Explain that function overloading allows you to define multiple functions with the same name but different parameter lists (different number or types of parameters). Operator overloading allows you to redefine the behavior of operators (e.g., +, -, \*, /) for user-defined types.

Example answer:

"Function overloading means you can have multiple functions with the same name but different parameters. The compiler figures out which version to call based on the arguments you pass. Operator overloading is similar, but instead of functions, you're redefining how operators like +, -, or * work for your own custom classes. For example, if I have a Vector class, I can overload the + operator to add two vectors together in a natural way. This makes my code more readable and intuitive."

## 19. What is RAII (Resource Acquisition Is Initialization)?

Why you might get asked this:

This question tests your understanding of a fundamental C++ idiom for resource management. Interviewers want to see if you know how to ensure that resources are properly acquired and released, even in the presence of exceptions. This helps the interviewer gauge your ability to handle more difficult c++ coding interview questions related to resource management.

How to answer:

Explain that RAII (Resource Acquisition Is Initialization) is a programming technique where resources are acquired during object construction and released during object destruction. This ensures that resources are automatically released when an object goes out of scope, even if exceptions are thrown. Use smart pointers as an example.

Example answer:

"RAII, which stands for Resource Acquisition Is Initialization, is a core principle in C++ for managing resources like memory, file handles, and network connections. The basic idea is that you tie the lifetime 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 in its destructor. This guarantees that resources are always cleaned up properly, even if exceptions are thrown. Smart pointers are a great example of RAII in action."

## 20. What are templates in C++?

Why you might get asked this:

Templates are a powerful feature in C++ that enable generic programming. This question assesses your understanding of how to write code that can work with different data types without being rewritten for each type. The interviewer is testing your ability to generalize solutions and write more reusable code, fundamental to answering c++ coding interview questions.

How to answer:

Explain that templates are a mechanism for writing generic code that can work with different data types. They allow you to define functions and classes that operate on type parameters rather than specific types. Templates can be used for both functions and classes.

Example answer:

"Templates in C++ are a way to write generic code that can work with different data types. You can think of them as blueprints for functions or classes. Instead of writing separate versions for int, float, or string, you write a single template that works with a placeholder type. The compiler then generates the specific code for each type you use the template with. I found templates really useful when implementing generic data structures like linked lists or trees, where I wanted to avoid writing separate versions for each possible data type."

## 21. What is the use of mutable keyword?

Why you might get asked this:

This question tests your understanding of const-correctness and how to modify members of a class even when the object is declared as const. Such knowledge helps in answering c++ coding interview questions related to complex class design.

How to answer:

Explain that the mutable keyword allows a member variable of a class to be modified even when the object is declared as const. This is useful for situations where you want to modify an internal state of an object without affecting its externally visible const-correctness.

Example answer:

"The mutable keyword allows you to modify a member variable of a class even when the object itself is declared as const. This is useful when you want to change some internal state of an object without breaking its logical const-ness. For instance, imagine a class that caches the results of an expensive calculation. You might want to update the cache even when the object is const, because that doesn't change the externally visible state of the object."

## 22. What is the difference between new and malloc()?

Why you might get asked this:

This question assesses your understanding of dynamic memory allocation in C++ and the differences between the C-style malloc() and the C++ new operator. This question tests your awareness of memory management best practices when answering c++ coding interview questions.

How to answer:

Explain that new is a C++ operator that allocates memory and calls the constructor of the object, while malloc() is a C function that allocates raw memory without calling the constructor. new also provides type safety and can be overloaded, while malloc() returns a void* and requires explicit casting.

Example answer:

"The main difference between new and malloc() is that new is a C++ operator that does two things: it allocates memory and then calls the constructor of the object. malloc(), on the other hand, is a C function that only allocates raw memory. It doesn't call any constructors. So, with malloc(), you have to manually initialize the object, which can be error-prone. Plus, new is type-safe because it returns a pointer of the correct type, while malloc() returns a void* that you have to cast. new can also be overloaded to customize memory allocation, which you can't do with malloc()."

## 23. Explain stack vs heap memory.

Why you might get asked this:

This question tests your understanding of how memory is organized and managed in a C++ program. Interviewers want to see if you understand the difference between stack and heap memory, their characteristics, and when to use each. A fundamental understanding of memory is crucial when answering c++ coding interview questions.

How to answer:

Explain that the stack is used for static memory allocation and stores local variables and function call information. It's managed automatically by the compiler and has limited size. The heap is used for dynamic memory allocation and is managed manually by the programmer. It's larger than the stack but requires careful management to prevent memory leaks.

Example answer:

"Stack memory and heap memory are two different ways of managing memory in a C++ program. The stack is where local variables and function call information are stored. It's managed automatically, meaning the compiler takes care of allocating and deallocating memory on the stack. It's also relatively small. The heap, on the other hand, is used for dynamic memory allocation. You have to manually allocate and deallocate memory on the heap using new and delete. The heap is much larger than the stack, but it's also more prone to memory leaks if you're not careful."

## 24. What is a smart pointer?

Why you might get asked this:

This question assesses your knowledge of smart pointers and their role in automating memory management. Interviewers want to see if you understand how smart pointers can prevent memory leaks and improve code safety. This helps assess your ability to handle more difficult c++ coding interview questions related to resource management.

How to answer:

Explain that smart pointers are template classes that encapsulate raw pointers and automatically manage their lifetime. Describe the different types of smart pointers: uniqueptr, sharedptr, and weak_ptr, and their respective use cases.

Example answer:

"Smart pointers are template classes that act like regular pointers but provide automatic memory management. They're designed to prevent memory leaks by ensuring that dynamically allocated memory is automatically deallocated when it's no longer needed. There are three main types: uniqueptr, which provides exclusive ownership; sharedptr, which allows multiple pointers to share ownership; and weakptr, which is a non-owning pointer that can observe a sharedptr without preventing it from being deallocated. I always prefer using smart pointers over raw pointers whenever possible to make my code safer and easier to maintain."

## 25. What is an iterator?

Why you might get asked this:

This question tests your understanding of iterators and their role in traversing containers. Interviewers want to see if you understand how iterators provide a generic way to access elements in different types of containers. You are being tested on your ability to use STL effectively in c++ coding interview questions.

How to answer:

Explain that an iterator is an object that acts like a pointer to an element in a container. It provides a way to access elements sequentially without exposing the underlying implementation of the container. Describe common iterator operations like incrementing, dereferencing, and comparing.

Example answer:

"An iterator is an object that lets you traverse through the elements of a container, like a vector or a list. You can think of it as a generalized pointer. Iterators provide a consistent interface for accessing elements, regardless of the specific type of container. You can increment an iterator to move to the next element, dereference it to get the value of the current element, and compare iterators to see if they point to the same location. They're really useful because they allow you to write generic algorithms that can work with different container types."

## 26. Explain difference between const pointer and pointer to const.

Why you might get asked this:

This question assesses your understanding of const-correctness and how it applies to pointers. Interviewers want to see if you understand the difference between a pointer that cannot be changed and a pointer that points to a constant value. A good grasp of const correctness and pointers can help you to answer more advanced c++ coding interview questions.

How to answer:

Explain that a const pointer (e.g., int const p) is a pointer that cannot be reassigned to point to a different memory location, but the value it points to can be modified. A pointer to const (e.g., const int p) is a pointer that points to a constant value, meaning the value it points to cannot be modified through that pointer, but the pointer itself can be reassigned.

Example answer:

"The difference is subtle but important. A const pointer, like int const p, is a pointer that cannot be changed to point to a different memory location. However, you can still modify the value that the pointer points to. On the other hand, a pointer to const, like const int p, is a pointer that points to a value that cannot be modified through that pointer. The pointer itself can be changed to point to a different memory location, but you can't use it to change the value it points to."

## 27. What is a lambda expression?

Why you might get asked this:

This question tests your familiarity with modern C++ features, specifically lambda expressions (introduced in C++11). Interviewers want to see if you understand how to create anonymous functions inline and their use cases. The use of lambda expressions helps to demonstrate your familiarity with current trends and best practices, and improve how you answer c++ coding interview questions.

How to answer:

Explain that a lambda expression is a concise way to define anonymous functions inline. It allows you to create a function object without explicitly defining a named function. Describe the syntax of a lambda expression and its use cases, such as passing a function as an argument to another function.

Example answer:

"A lambda expression is a compact way to create anonymous functions directly in your code. It's basically a function without a name that you can define inline where you need it. This is really useful when you want to pass a small piece of code as an argument to another function, like when sorting a vector with a custom comparison function. Lambda expressions make the code much more concise and readable compared to defining a separate named function."

## 28. What is a dangling pointer?

Why you might get asked this:

This question assesses your understanding of pointer-related errors and how to avoid them. Interviewers want to see if you understand the dangers of dangling pointers and how they can lead to undefined behavior. Understanding dangling pointers is essential for addressing memory management c++ coding interview questions.

How to answer:

Explain that a dangling pointer is a pointer that points to a memory location that has been freed or deallocated. Accessing a dangling pointer can lead to unpredictable behavior, crashes, or security vulnerabilities.

Example answer:

"A dangling pointer is a pointer that points to a memory location that has already been freed or deallocated. This happens when you delete the memory that a pointer is pointing to, but you don't set the pointer to nullptr. If you then try to dereference that dangling pointer, you're accessing memory that's no longer valid, which can lead to crashes or unpredictable behavior. It's best practice to always set a pointer to nullptr after deleting the memory it points to in order to avoid this issue."

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

Why you might get asked this:

This question tests your understanding of the subtle differences between struct and class in C++. Interviewers want to see if you know the default access specifier and when to use each. Such subtle differences often arise in **c++ coding interview questions