Custom Exceptions

While you can throw exceptions of fundamental types like `int` or `const char*`, it is a much better practice to use custom exception classes. The C++ Standard Library provides a hierarchy of exception classes (like `std::exception`, `std::runtime_error`, `std::logic_error`) that you can use, but often it's beneficial to create your own. A custom exception class is simply a class that you design to represent a specific type of error in your application. Typically, these classes inherit from `std::exception`. The `std::exception` base class provides a virtual member function called `what()` that returns a C-style string describing the exception. By inheriting from it and overriding `what()`, your custom exceptions can integrate smoothly with the standard exception handling mechanisms. For example, if you are writing a banking application, you might create an `InsufficientFundsError` class. When a withdrawal fails, you can `throw InsufficientFundsError("Not enough balance");`. The calling code can then have a specific `catch (const InsufficientFundsError& e)` block to handle that particular scenario, perhaps by showing a user-friendly message. Using custom exception classes makes your error handling much more precise and your code more readable and maintainable. You can add member variables to your custom exception classes to carry more detailed information about the error that occurred.