Handling Python Exceptions CL-24

Handling Python Exceptions

What are Exceptions in Python?

In Python, "exceptions" are like special messages that pop up when something goes wrong in a computer program. Think of them as red flags that tell you there's a problem. These problems could be things like trying to divide by zero (which is impossible) or trying to open a file that doesn't exist.

Why Handling Exceptions is Important for Reliable Programs

Imagine you're building a robot, and you give it a set of instructions. If something unexpected happens, like the robot bumps into a wall or the battery runs out, you want the robot to respond in a smart way, not just stop working or crash.

In the same way, when we write computer programs, we want them to be smart too. Handling exceptions helps us make our programs smarter and more reliable. It allows our programs to react sensibly when things don't go as planned. Without handling exceptions, our programs might just stop or show weird error messages, which isn't very helpful for users. So, handling exceptions is like teaching our programs to deal with problems gracefully and keep running smoothly.

Common Built-in Exceptions

let's discuss some common built-in exceptions in Python using simple language and examples:

1. SyntaxError

What it is: A SyntaxError happens when you write code that doesn't follow the rules of Python's language. It's like making grammar mistakes in a sentence.

Example: If you forget to close a parenthesis, like this:

• python
  print("Hello, world!"
  

  Python will raise a SyntaxError and show you where it got confused.
  Output:

  arduino
  File "<stdin>", line 1
  print("Hello, world!"
        ^
  SyntaxError: unexpected EOF while parsing

2. TypeError

What it is: A TypeError occurs when you try to use a variable or do an operation with a data type that doesn't match what Python expects. It's like trying to add apples and oranges.

Example: If you try to add a number and a string directly, like this:

• python
  result = 5 + "2"
  

  Python will raise a TypeError because it can't mix numbers and strings like that.
  Output:

  bash
  TypeError: unsupported operand type(s) for +: 'int' and 'str'
  

3. ZeroDivisionError:

What it is: This error happens when you try to divide a number by zero. It's like trying to share a pizza among zero people; it just doesn't make sense.

Example: If you attempt to divide by zero, like this:

• python
  result = 10 / 0
  

  Python will raise a ZeroDivisionError because dividing by zero isn't possible.
  Output:

  vbnet
  ZeroDivisionError: division by zero
  

4. FileNotFoundError:

What it is: A FileNotFoundError occurs when you try to open or access a file that doesn't exist on your computer.

Example: If you try to open a file that's not there, like this:

• python
  with open("nonexistent.txt", "r") as file:
      content = file.read()

  
  Python will raise a FileNotFoundError because it can't find the file you're asking for.
  Output:

  vbnet
  FileNotFoundError: [Errno 2] No such file or directory: 'nonexistent.txt'
  

These common exceptions help Python tell you what went wrong in your code so you can fix it. Understanding them can make it easier to write programs that work correctly.

Try-Except Blocks

Let's explain the basic structure of a try-except block in Python using simple language and examples:

1. Try-Except Block Basics:

A try-except block is like a safety net in Python. It helps you catch and deal with errors so that your program doesn't crash.

The basic structure looks like this:

• python
  try:
      # Code that might cause an error
  except SomeException:
      # Code to run if that specific error happens

2. Catching Specific Exceptions:

You can specify which type of error (exception) you want to catch after the except keyword. This way, you can handle different errors in different ways.

For example, if you're trying to divide two numbers and want to handle a ZeroDivisionError:

• python
  try:
      result = 10 / 0
  except ZeroDivisionError:
      print("Oops! You can't divide by zero.")

  Output:

  rust
  Oops! You can't divide by zero.
  

• 
  
• You can catch multiple types of exceptions in the same try-except block by separating them with commas:

  python
  try:
      value = int("hello")
  except (ValueError, TypeError):
      print("Oops! Something went wrong with the conversion.")

  Output:

  csharp
  Oops! Something went wrong with the conversion.
  

3. Handling Exceptions Gracefully:

Inside the except block, you can write code to handle the error gracefully. This means doing something other than crashing the program.

For instance, if you're reading data from a file, you might handle a FileNotFoundError like this:

• python
  try:
      with open("nonexistent.txt", "r") as file:
          content = file.read()
  except FileNotFoundError:
      print("The file you're looking for doesn't exist.")

  Output:

  python
  The file you're looking for doesn't exist.
  

By using try-except blocks, you can make your program more robust and user-friendly by handling expected errors in a way that won't disrupt the entire program. It's like having a backup plan for when things go wrong.

Handling Multiple Exceptions

Let's explain how to handle multiple exceptions in Python using easy language and examples in detail:

1. Handling Multiple Exceptions with Multiple Except Blocks:

Sometimes, you want to handle different types of exceptions in unique ways. You can do this by using multiple except blocks, each for a specific exception type.

Here's how it works:

• python
  try:
      # Code that might cause an error
  except ExceptionType1:
      # Code to run if ExceptionType1 occurs
  except ExceptionType2:
      # Code to run if ExceptionType2 occurs

• 
  
• For example, you might want to handle a ValueError and a TypeError differently:

  python
  try:
      value = int("hello")
  except ValueError:
      print("Oops! There's a problem with the value.")
  except TypeError:
      print("Oops! There's a type mismatch.")

  Output:

  vbnet
  Oops! There's a problem with the value.
  

2. Handling Multiple Exceptions with a Single Block:

If you want to handle multiple exceptions in the same way, you can group them together in a single except block using parentheses.

Here's how it looks:

• python
  try:
      # Code that might cause an error
  except (ExceptionType1, ExceptionType2):
      # Code to run if either ExceptionType1 or ExceptionType2 occurs

• 
  
• For example, you might want to handle both FileNotFoundError and PermissionError in a similar way when dealing with file operations:

  python
  try:
      with open("nonexistent.txt", "r") as file:
          content = file.read()
  except (FileNotFoundError, PermissionError):
      print("Oops! There's a problem with the file.")

  Output:

  vbnet
  Oops! There's a problem with the file.
  

Handling multiple exceptions this way keeps your code clean and concise when you need to respond to several different types of errors.

The else and finally Clauses

Let's talk about the else and finally, clauses in Python exception handling using straightforward language and examples:

1. The else Clause:

The else clause is like a bonus section in a try-except block. It contains code that runs only if there are no exceptions raised in the try block.

Here's how it's structured:

• python
  try:
      # Code that might cause an error
  except ExceptionType:
      # Code to handle the exception
  else:
      # Code that runs when no exception occurs

• 
  
• For example, you can use the else clause to perform an action when reading a file successfully:

  python
  try:
      with open("my_file.txt", "r") as file:
          content = file.read()
  except FileNotFoundError:
      print("File not found.")
  else:
      print("File read successfully.")

  Output (if the file exists):

  arduino
  File read successfully.
  

2. The finally Clause:

The finally clause is like a safety net for your code. It contains code that will always run, regardless of whether an exception occurred or not.

It's structured like this:

• python
  try:
      # Code that might cause an error
  except ExceptionType:
      # Code to handle the exception
  finally:
      # Code that always runs

• 
  
• For example, you can use the finally clause to ensure that a file is always closed, whether an exception occurred or not:

  python
  try:
      file = open("my_file.txt", "r")
      content = file.read()
  except FileNotFoundError:
      print("File not found.")
  finally:
      file.close()

  This guarantees that the file is closed properly, even if there was an error reading it or if everything went smoothly.
  
  In summary, the else clause lets you execute code when no exceptions happen , while the finally clause ensures that specific code always runs , making it useful for tasks like cleaning up resources (e.g., closing files or database connections) regardless of what happens in your program.

Raising Exceptions

Let's discuss raising custom exceptions in Python using simple language and examples:

1. Raising Custom Exceptions:

In Python, you can create your own custom exceptions to handle specific situations in your code. To do this, you use the raise statement .

Here's how you can raise a custom exception:

• python
  raise CustomException("A message explaining the error")
  

  CustomException is the name of your custom exception class, and you can provide a descriptive message to explain the error.
  
  

• 2. When to Raise Custom Exceptions:

• You might want to raise custom exceptions when you encounter a situation in your code that doesn't fit any of Python's built-in exceptions, but you still need to communicate an error or specific condition.
  
  

• 3. Why Raise Custom Exceptions:

• Custom exceptions make your code more readable and maintainable because they provide clear, meaningful error messages tailored to your application's logic.
  
  They also allow you to handle errors in a way that's appropriate for your program. For example, you can raise a custom exception when a user enters invalid input or when a specific condition isn't met.
  
  Example: Raising a Custom Exception
• 
  Let's say you're building a program that calculates the price of items in an online store. You want to ensure that the price of an item is always a positive number. If it's not, you want to raise a custom exception called InvalidPriceError . Here's how you can do that:

python
class InvalidPriceError(Exception):
    """Custom exception for invalid prices."""
    pass

def calculate_total_price(item_price):
    if item_price < 0:
        raise InvalidPriceError("Price cannot be negative.")
    return item_price

try:
    price = calculate_total_price(-10)
except InvalidPriceError as e:
    print(f"Error: {e}")
else:
    print(f"Total Price: ${price}")

Output (when the price is negative):

javascript
Error: Price cannot be negative.

Output (when the price is positive):

bash
Total Price: $10

In this example, we've created a custom exception InvalidPriceError to handle cases where the item price is negative. This custom exception provides a clear message explaining the error, making it easier to understand and troubleshoot issues in your code.

Exception Handling Best Practices

Let's discuss some best practices for exception handling in Python using simple language:

1. Use Specific Exceptions:

It's a good practice to catch and handle specific exceptions rather than using a general catch-all exception. This helps you pinpoint and address the exact issue in your code.

• python
  try:
      # Code that might cause a specific error
  except SpecificException:
      # Handle the specific error

  For example, if you expect a ValueError, catch that specific exception instead of using a generic except block:

  python
  try:
      value = int("hello")
  except ValueError:
      print("Invalid value provided.")

2. Avoid Bare except Blocks:

Avoid using a bare except block without specifying the type of exception. This can make debugging difficult because it catches all exceptions, including those you may not have anticipated.

• python
  try:
      # Code that might cause an error
  except:
      # This catches all exceptions, which is generally a bad practice

  Instead, be specific about the exceptions you want to catch:

  python
  try:
      # Code that might cause a specific error
  except SpecificException:
      # Handle the specific error

3. Avoid Overly Broad try Blocks:

Keep the code within your try blocks as small as possible. Don't wrap large sections of code in a single try. Instead, use multiple smaller try blocks if needed. This makes it easier to locate and handle errors.

• python
  try:
      # Large section of code
  except SpecificException:
      # Handle the specific error

  Instead, break it down into smaller, more focused try blocks:

  python
  try:
      # Code block 1
  except SpecificException:
      # Handle the error for code block 1
  
  try:
      # Code block 2
  except SpecificException:
      # Handle the error for code block 2

4. Provide Helpful Error Messages:

Include informative error messages when raising and handling exceptions. Clear and descriptive error messages make it easier to identify and fix issues in your code.

• python
  try:
      value = int("hello")
  except ValueError:
      print("Invalid value provided. Please enter a valid number.")

5. Log Errors:

Consider logging exceptions to a file or system log for debugging and monitoring purposes. This can be especially useful in production environments to track and diagnose issues.

6. Plan Your Exception Strategy:

Think about how your code should react to exceptions. Should it retry the operation, prompt the user, or take another specific action? Plan your exception-handling strategy accordingly.

By following these best practices, you can make your code more robust, maintainable, and easier to debug, ultimately leading to more reliable and user-friendly applications.

Handling File Exceptions Best Practices

Let's discuss how to handle file-related exceptions in Python using simple language and examples:

1. Handling File Exceptions:

File-related exceptions can occur when you work with files in Python. Two common file exceptions are FileNotFoundError and PermissionError.

2. FileNotFoundError:

This exception occurs when you try to access a file that doesn't exist.

You can handle it like this:

• python
  try:
      with open("myfile.txt", "r") as file:
          content = file.read()
  except FileNotFoundError:
      print("The file doesn't exist.")

  Output (if the file doesn't exist):

  rust
  The file doesn't exist.
  

3. PermissionError:

This exception happens when you try to access a file without the necessary permissions (e.g., trying to write to a read-only file).

You can handle it like this:

• python
  try:
      with open("readonly.txt", "w") as file:
          file.write("This is a write operation.")
  except PermissionError:
      print("Permission denied. You don't have the necessary permissions to write to this file.")

  Output (if you don't have write permissions):

  vbnet
  Permission denied. You don't have the necessary permissions to write to this file.
  

4. Demonstrating File Operations within Try-Except:

You can perform various file operations within a try-except context. Here's a complete example that demonstrates opening, reading, writing, and closing a file with error handling:

• python
  try:
      # Attempt to open a file for writing
      with open("output.txt", "w") as file:
          # Attempt to write to the file
          file.write("Hello, World!")
  
      # Attempt to open the same file for reading
      with open("output.txt", "r") as file:
          # Attempt to read from the file
          content = file.read()
          print("File content:", content)
  except FileNotFoundError:
      print("The file doesn't exist.")
  except PermissionError:
      print("Permission denied. You don't have the necessary permissions.")
  except Exception as e:
      print("An error occurred:", str(e))

  Output:

  arduino
  File content: Hello, World!
  

In this example, we've demonstrated how to handle common file-related exceptions such as FileNotFoundError and PermissionError while performing file operations. Handling these exceptions gracefully ensures your program doesn't crash and can provide meaningful error messages to users or log errors for debugging.

Custom Exception Classes Best Practices

Let's discuss creating custom exception classes in Python using simple language and examples:

1. Creating Custom Exception Classes:

In Python, you can create your own custom exception classes by defining new classes that inherit from the built-in Exception class or one of its subclasses. This allows you to create exceptions tailored to your application's specific needs.

To create a custom exception class, you can define a new class that inherits from Exception like this:

• python
  class CustomException(Exception):
      pass
  

2. When to Create Custom Exception Classes:

You might want to create custom exception classes when you encounter specific situations in your code that aren't adequately covered by Python's built-in exceptions. Custom exceptions help make your code more expressive and provide context-specific error messages.

3. Why Create Custom Exception Classes:

Custom exception classes allow you to handle errors in a way that makes sense for your application. They also make it easier to distinguish between different types of errors, improving the clarity and maintainability of your code.

Examples of Custom Exception Classes:

Example 1: Custom ValueError

Suppose you are building a program that validates user input. You can create a custom InvalidInputError class to raise when the user provides invalid data:

python
class InvalidInputError(ValueError):
    pass

def get_user_age():
    age = int(input("Enter your age: "))
    if age < 0 or age > 120:
        raise InvalidInputError("Invalid age provided. Age must be between 0 and 120.")
    return age

try:
    user_age = get_user_age()
    print("User's age:", user_age)
except InvalidInputError as e:
    print("Error:", e)

Output (when an invalid age is provided):

yaml
Enter your age: 150
Error: Invalid age provided. Age must be between 0 and 120.

Output (when a valid age is provided):

yaml
Enter your age: 30
User's age: 30

Example 2: Custom FileError

Suppose you are developing a file processing application, and you want to create a custom exception class for file-related errors:

python
class FileError(Exception):
    pass

def read_file(filename):
    try:
        with open(filename, "r") as file:
            content = file.read()
        return content
    except FileNotFoundError:
        raise FileError(f"File not found: {filename}")
    except PermissionError:
        raise FileError(f"Permission denied: {filename}")

try:
    file_content = read_file("nonexistent.txt")
    print("File content:", file_content)
except FileError as e:
    print("Error:", e)

Output (when the file doesn't exist):

arduino
Error: File not found: nonexistent.txt

In these examples, custom exception classes (InvalidInputError and FileError) are created to provide specific and informative error messages for the given situations. Custom exceptions help improve the clarity and robustness of your code by allowing you to handle errors in a way that makes sense for your application.

Module-Level Exception Handling Best Practices

Let's discuss module-level exception handling in Python using simple language and examples:

1. Module-Level Exception Handling:

Module-level exception handling refers to handling exceptions at the level of an entire module or script. This means dealing with errors that might occur across multiple functions or code sections within the module.

When an exception occurs in a module, it can affect the entire program if not properly handled. Therefore, it's essential to consider how exceptions are managed at the module level.

2. Propagating Exceptions Up the Call Stack:

When an exception occurs within a function, Python looks for a nearby try-except block to handle it. If it doesn't find one, the exception propagates (moves) up the call stack to higher-level functions and ultimately to the module level.

If the exception isn't handled at any point along the way, it will propagate up to the module level. If it's still not handled there, it may cause the entire program to terminate.

Example: Module-Level Exception Handling

Let's illustrate module-level exception handling with an example. Suppose you have a Python program that reads and processes data from a file, performs calculations, and then displays the results. If an exception occurs at any point in this process, you want to catch it at the module level to provide a clear error message and gracefully exit the program.

python
def read_data(filename):
    try:
        with open(filename, "r") as file:
            data = file.read()
        return data
    except FileNotFoundError:
        raise Exception("File not found: " + filename)

def calculate_average(data):
    try:
        values = [int(x) for x in data.split()]
        return sum(values) / len(values)
    except (ValueError, ZeroDivisionError):
        raise Exception("Invalid data format or division by zero")

def main():
    try:
        data = read_data("data.txt")
        average = calculate_average(data)
        print("Average:", average)
    except Exception as e:
        print("An error occurred:", str(e))

if __name__ == "__main__":
    main()

In this example, if any exceptions occur in the read_data or calculate_average functions, they are caught and raised as a custom Exception at the module level (inside the main function). This provides a clear error message and ensures that the program exits gracefully without crashing.

By handling exceptions at the module level, you can control how errors are reported and prevent unexpected program termination, making your program more robust and user-friendly.

Debugging with Exceptions

Let's discuss how exceptions can be valuable for debugging code in simple terms and provide examples of printing exception information to gain insights into errors:

1. Valuable for Debugging:

Exceptions are like helpful messages that Python gives you when something goes wrong in your code. They can be incredibly valuable for finding and fixing errors during development.

When an exception occurs, Python not only tells you what went wrong but also where it happened in your code. This location information is like a map that guides you to the problem area.

2. Printing Exception Information:

You can print exception information to gain insights into errors using try-except blocks. Python provides access to valuable details about the error, including its type and the message associated with it.

Here's how you can do it:

• python
  try:
      # Code that might cause an error
  except ExceptionType as e:
      print(f"An error of type {type(e).__name__} occurred: {str(e)}")

Example: Debugging with Exceptions

Let's say you're building a program that calculates the average of a list of numbers, but there's a bug in your code. You can use exceptions to help debug it:

python
def calculate_average(numbers):
    try:
        return sum(numbers) / len(numbers)
    except ZeroDivisionError as e:
        print(f"Error: {type(e).__name__} - {str(e)}")
    except Exception as e:
        print(f"An unexpected error occurred: {type(e).__name__} - {str(e)}")

numbers = []  # An empty list, which will cause a ZeroDivisionError

try:
    average = calculate_average(numbers)
    print("Average:", average)
except Exception as e:
    print(f"An error occurred in the main program: {type(e).__name__} - {str(e)}")

Output (ZeroDivisionError):

vbnet
Error: ZeroDivisionError - division by zero
An error occurred in the main program: ZeroDivisionError - division by zero

In this example, an empty list caused a ZeroDivisionError in the calculate_average function. By catching and printing this exception, you can immediately see what type of error occurred and the associated error message, which helps you locate and fix the issue in your code.

Using exceptions for debugging allows you to identify problems more efficiently and make your code more reliable.

Exception Hierarchy and Catch-All Handling:

Let's explain the Python exception hierarchy and how to catch multiple exceptions using base classes like Exception in simple language:

1. Python Exception Hierarchy:

In Python, exceptions are organized into a hierarchy or a tree-like structure. At the top of this hierarchy is the base class called BaseException, and all other exceptions inherit from it.

Some common exception types, like Exception, ValueError, and TypeError, are lower down in the hierarchy, which means they are more specialized.

This hierarchy allows you to catch specific exceptions or groups of exceptions based on their relationship in the tree.

2. Catching Multiple Exceptions with Base Classes:

You can catch multiple exceptions using base classes like Exception by specifying these base classes in the except block. This way, you can catch a group of related exceptions with a single block.

For example, you can catch multiple exceptions like this:

• python
  try:
      # Code that might cause an error
  except (ExceptionType1, ExceptionType2) as e:
      # Code to handle these exceptions


Here, ExceptionType1 and ExceptionType2 are exceptions that inherit from the same base class (e.g., Exception). If either of these exceptions occurs, the code inside the except block will run.

Example: Catching Multiple Exceptions with Exception

Let's say you're working with user input, and you want to handle both ValueError (invalid input) and TypeError (incorrect data type) exceptions:

python
try:
    user_input = input("Enter a number: ")
    number = int(user_input)
    result = 10 / number
except (ValueError, TypeError) as e:
    print(f"An error occurred: {type(e).__name__} - {str(e)}")
except ZeroDivisionError as e:
    print(f"Division by zero: {type(e).__name__} - {str(e)}")
else:
    print(f"Result: {result}")

Output (ValueError):

csharp
Enter a number: hello
An error occurred: ValueError - invalid literal for int() with base 10: 'hello'

Output (ZeroDivisionError):

csharp
Enter a number: 0
Division by zero: ZeroDivisionError - division by zero

In this example, we catch both ValueError and TypeError exceptions together using the except (ValueError, TypeError) block, which handles invalid input and incorrect data type issues. Then, we handle ZeroDivisionError separately. This way, we can provide specific error messages for each type of exception while keeping our code organized and concise.

Testing Exception Handling

Let's discuss strategies for testing exception handling code in simple language:

1. Unit Tests:

Unit tests are a way to check if your exception handling code works as expected. You write small, focused tests that evaluate specific parts of your code, including how it handles exceptions.

Here's how you can create a unit test for exception handling:

• Define a test case: Identify the scenario where an exception might occur.
• Write test code: Create a test that triggers the exception.
• Use testing frameworks: Python has built-in testing libraries like unittest and third-party libraries like pytest to help you organize and run tests.

2. Testing Edge Cases:

Edge cases are scenarios that are at the "edge" of what's expected or typical. Testing exception handling with edge cases can help you identify potential vulnerabilities in your code.

For example, if you're handling user input, consider testing for cases like empty input, extremely large or small values, or unexpected characters.

Example: Testing Exception Handling

Suppose you have a function that divides two numbers, and you want to test its exception handling:

python
def divide_numbers(a, b):
    try:
        result = a / b
        return result
    except ZeroDivisionError:
        return "Cannot divide by zero"

Now, you can create unit tests, including edge cases, using a testing framework like unittest:

python
import unittest

class TestDivision(unittest.TestCase):
    
    def test_divide_valid(self):
        self.assertEqual(divide_numbers(10, 2), 5)
    
    def test_divide_by_zero(self):
        self.assertEqual(divide_numbers(5, 0), "Cannot divide by zero")
    
    def test_invalid_input(self):
        self.assertEqual(divide_numbers("hello", 2), None)
    
    def test_edge_case_large_numbers(self):
        self.assertEqual(divide_numbers(10**100, 2), 5*10**99)
    
    def test_edge_case_small_numbers(self):
        self.assertEqual(divide_numbers(1, 10**100), 0)

if __name__ == '__main__':
    unittest.main()

In this example, we create various test cases, including valid division, division by zero, invalid input, and edge cases with very large and very small numbers. These tests help ensure that our exception handling code behaves correctly in different scenarios.

By testing your exception handling code thoroughly, you can increase the reliability and robustness of your application, ensuring that it responds appropriately to unexpected situations.

Handling Python Exceptions Advanced Topics

For a more advanced audience, let's discuss some advanced topics related to handling Python exceptions:

1. Custom Context Managers:

Custom context managers allow you to manage resources, such as files, database connections, or network sockets, in a clean and Pythonic way. They can be especially useful for ensuring proper resource cleanup when exceptions occur.


To create a custom context manager, you define a class with __enter__ and __exit__ methods. The __enter__ method sets up the resource, and the __exit__ method handles cleanup.

Example: Custom Context Manager

python
class CustomFileHandler:
    def __init__(self, filename, mode):
        self.filename = filename
        self.mode = mode

    def __enter__(self):
        self.file = open(self.filename, self.mode)
        return self.file

    def __exit__(self, exc_type, exc_value, traceback):
        self.file.close()

# Usage of the custom context manager
with CustomFileHandler("example.txt", "w") as file:
    file.write("Hello, World!")

In this example, the CustomFileHandler class is a custom context manager that handles file opening and closing. It ensures that the file is closed properly even if an exception occurs.

2. Try-Except-Else-Finally Combinations:

You can combine try, except, else, and finally blocks for advanced exception handling scenarios.

The else block is executed when no exception occurs in the try block. It's useful for placing code that should run only when the try block succeeds.

The finally block always runs, regardless of whether an exception occurred. It's commonly used for cleanup tasks like closing files or releasing resources.

Example: Try-Except-Else-Finally Combination

python
try:
    value = int(input("Enter a number: "))
except ValueError:
    print("Invalid input. Please enter a valid number.")
else:
    print(f"Entered number: {value}")
finally:
    print("Execution completed.")

3. The with Statement for Resource Management:

The with statement simplifies resource management, especially when dealing with files, by automatically taking care of setup and cleanup.

It is often used with context managers, like the built-in open function, to ensure proper resource handling.

Example: Using with Statement with File Handling

python
with open("example.txt", "r") as file:
    content = file.read()
    # File is automatically closed when the block exits

These advanced topics can help you write more robust and clean code when handling exceptions, managing resources, and controlling program flow. They are particularly valuable for experienced Python developers working on complex projects.