Top C++ Exception Handling Interview Questions and Answers for 7 years experience

1. What is the purpose of exception handling in C++?

   • Answer: Exception handling in C++ is a mechanism to gracefully handle runtime errors (exceptions) that might occur during program execution. It separates error-handling code from the main logic, improving code readability and maintainability. It prevents program crashes by allowing controlled responses to unexpected situations.

2. Explain the `try`, `catch`, and `throw` keywords.

   • Answer: `try` block: Encloses the code that might throw an exception. `throw`: Used to explicitly throw an exception object. `catch` block: Handles exceptions thrown within the corresponding `try` block. Multiple `catch` blocks can handle different exception types.

3. What are the different types of exceptions in C++?

   • Answer: C++ exceptions can be broadly classified as standard exceptions (defined in ``) like `std::exception`, `std::runtime_error`, `std::logic_error`, and custom exceptions defined by the programmer.

4. How do you handle exceptions that might be thrown from functions you call?

   • Answer: By wrapping the function call within a `try` block and providing appropriate `catch` blocks to handle any exceptions that the called function might throw.

5. Explain the concept of exception specifications (deprecated).

   • Answer: Exception specifications (e.g., `void foo() throw(int)`) were used to declare which exceptions a function could throw. However, they are deprecated in modern C++ because they were often misused and could lead to unexpected behavior. Modern C++ prefers relying on good documentation and testing to manage exceptions.

6. What is the `std::exception` class and its role?

   • Answer: `std::exception` is the base class for many standard exception classes. It provides a common interface and serves as a base for creating custom exception classes.

7. Describe the difference between `std::runtime_error` and `std::logic_error`.

   • Answer: `std::runtime_error` represents exceptions that occur due to unforeseen circumstances during program execution (e.g., file not found). `std::logic_error` represents exceptions that result from errors in the program's logic (e.g., invalid arguments).

8. How do you create and throw a custom exception class? Provide an example.

   • Answer: You create a custom exception class by deriving from `std::exception` or one of its subclasses and overriding the `what()` method. Example: class MyException : public std::runtime_error { public: MyException(const std::string& msg) : std::runtime_error(msg) {} };

9. Explain exception handling and resource management. How can you ensure resources are released even if an exception occurs?

   • Answer: Use RAII (Resource Acquisition Is Initialization) with smart pointers (`std::unique_ptr`, `std::shared_ptr`) to ensure resources are automatically released when they go out of scope, even if exceptions are thrown. Avoid using `delete` directly within `try` blocks.

10. What is the importance of stack unwinding in exception handling?

    • Answer: Stack unwinding is the process of releasing resources and destructing objects on the stack as the program's execution flow returns from functions that were called within a `try` block that threw an exception. This is crucial for resource management and preventing memory leaks.

11. Discuss the difference between `catch(...)` and specific `catch` blocks. When should you use each?

    • Answer: `catch(...)` catches any exception. It's generally considered a last resort because it obscures the specific type of exception, making debugging more difficult. Specific `catch` blocks should be used whenever possible to handle different exceptions differently. `catch(...)` might be acceptable for logging unexpected exceptions before program termination.

12. What is exception safety? Describe the different levels of exception safety.

    • Answer: Exception safety refers to the ability of a function or code block to maintain data integrity and resource management even when exceptions are thrown. Levels include: nothrow guarantee (no exceptions), strong guarantee (atomic operations, rollback on failure), basic guarantee (data is consistent, but resources may be leaked), no guarantee (arbitrary behavior).

13. How can you avoid exceptions from being silently ignored?

    • Answer: Always include a `catch(...)` block as the last catch block to handle any unhandled exceptions and log them. Avoid bare `catch` blocks unless absolutely necessary.

Thank you for reading our blog post on 'Top C++ Exception Handling Interview Questions and Answers for 7 years experience'.We hope you found it informative and useful.Stay tuned for more insightful content!