**Course Title:** Mastering C#: From Fundamentals to Advanced Programming **Section Title:** Error Handling and Exception Management **Topic:** Understanding the exception hierarchy in C#. Exception handling is a crucial aspect of programming, enabling developers to robustly manage and recover from unexpected errors that may occur during runtime. In this topic, we will delve into the exception hierarchy in C#, examining its structure, key concepts, and practical applications. **The Exception Hierarchy** In C#, all exceptions are derived from the `System.Exception` class, which inherits from the `System.Runtime.Serialization.ISerializable` and `System.Runtime.InteropServices._Exception` interfaces. This base class serves as the foundation for all exceptions in the .NET Framework. Here's a high-level overview of the exception hierarchy: ```csharp System.Object System.Exception System.SystemException System.ApplicationException System.Runtime.InteropServices.ExternalException ``` Some key exceptions that inherit from `System.Exception` include: ```csharp System.EntryPointNotFoundException System.NotSupportedException System.InvincibleException System.InvalidCastException System.InvalidOperationException System.ArgumentException System.ArgumentOutOfRangeException ``` **System.SystemException** `System.SystemException` is the base class for system exceptions, which are typically thrown by the runtime environment or .NET Framework classes. It's worth noting that many common exceptions, such as `NullReferenceException` and `IOException`, inherit from `System.SystemException`. **System.ApplicationException** `System.ApplicationException` is the base class for application-specific exceptions. It's used as a base class for custom exceptions. **System_EXTERNAL Exceptions and SEHExceptions** `System.Runtime.InteropServices.ExternalException` is used to handle exceptions originating from external sources, while `System.Runtime.InteropServices.SehException` represents a Structured Exception Handling (SEH) exception. **Custom Exceptions** Custom exceptions are an important part of a robust error handling strategy. They enable you to create domain-specific exception classes that convey meaningful information to users or developers. Best Practices: * Always inherit custom exceptions from `System.ApplicationException` or another custom exception class. * Ensure exceptions are serializable (inherit from `System.Runtime.Serialization.ISerializable`) when used in distributed or cross-process scenarios. * Implement a clear and consistent exception strategy across your application. Practical Example -------------------- Here's a basic example illustrating the creation of a custom exception and its usage in a console application. ```csharp using System; public class InsufficientBalanceException : ApplicationException { public InsufficientBalanceException(string message) : base(message) { } } public class Program { public static void Main() { try { Console.WriteLine("Enter initial bank balance: "); decimal balance = decimal.Parse(Console.ReadLine()); if (balance < 100) { throw new InsufficientBalanceException("Initial balance is too low."); } Console.WriteLine("Account balance set successfully."); } catch (FormatException e) { Console.WriteLine($"Invalid input: {e.Message}"); } catch (InsufficientBalanceException e) { Console.WriteLine($"Error: {e.Message}"); } } } ``` Conclusion ---------- In this topic, we explored the exception hierarchy in C#. Understanding these conceptual frameworks is vital for tackling error handling and creating applications that can recover from unexpected runtime errors. In the next topic, we'll discuss the practical application of try-catch blocks for robust error handling. External Resource: You can learn more about exception handling best practices and strategies at [Microsoft Docs - Exception Handling (C# Programming Guide)](https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/exceptions/index). We encourage you to leave a comment with your thoughts or questions after completing this topic.