**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** File Handling and Exception Management **Topic:** Handling exceptions: begin, rescue, ensure, and raise **Introduction:** In Ruby, exceptions are an essential part of error handling. They allow you to handle specific errors that may occur during the execution of your program. In this topic, we will cover the basics of exception handling in Ruby, including the `begin`, `rescue`, `ensure`, and `raise` keywords. **What are Exceptions?** An exception is an event that occurs during the execution of a program that disrupts the normal flow of instructions. Exceptions can be caused by various factors such as invalid input, file not found, or network errors. **The `begin` Keyword:** The `begin` keyword is used to enclose a block of code that may potentially raise an exception. If an exception occurs within the `begin` block, it will be caught by the `rescue` block. ```ruby begin # Code that may raise an exception x = 1 / 0 rescue Exception => e # Handle the exception puts "An error occurred: #{e.message}" end ``` **The `rescue` Keyword:** The `rescue` keyword is used to specify the type of exception that you want to catch. You can also specify a block of code to handle the exception. ```ruby begin # Code that may raise an exception x = 1 / 0 rescue ZeroDivisionError => e # Handle the exception puts "Cannot divide by zero: #{e.message}" rescue Exception => e # Handle any other exceptions puts "An unexpected error occurred: #{e.message}" end ``` **The `ensure` Keyword:** The `ensure` keyword is used to specify a block of code that should always be executed, regardless of whether an exception occurred or not. ```ruby begin # Code that may raise an exception x = 1 / 0 ensure # Code that should always be executed puts "Cleaning up..." end ``` **The `raise` Keyword:** The `raise` keyword is used to explicitly raise an exception. You can also specify a custom error message. ```ruby # Raise a custom error raise "Something went wrong!" ``` **Best Practices for Exception Handling:** 1. Always handle exceptions that you can anticipate. 2. Use specific exception types to catch only the exceptions you expect. 3. Keep your exception handling code concise and focused on handling the exception. 4. Use the `ensure` keyword to ensure that critical code is always executed. **Practical Takeaways:** 1. Use the `begin` keyword to enclose code that may potentially raise an exception. 2. Use the `rescue` keyword to catch specific exceptions. 3. Use the `ensure` keyword to ensure that critical code is always executed. 4. Use the `raise` keyword to explicitly raise an exception. **Exercise:** Write a program that handles exceptions when reading from a file. Use the `begin`, `rescue`, and `ensure` keywords to handle the exception. ```ruby # Read from a file begin file = File.open("example.txt", "r") contents = file.read file.close rescue IOError => e # Handle the exception puts "Error reading from file: #{e.message}" ensure # Close the file if it was opened file.close if file end ``` **Leave a comment or ask for help if you have any questions or need further clarification!** This concludes the topic on handling exceptions in Ruby. In the next topic, we will cover best practices for error handling.