What exception handling constructs exist in Python?

In Python, the following constructs are used for exception handling:

• try...except: The core of exception handling. The try block contains code that may raise an exception. If an exception occurs, the corresponding except block is executed.

  # Examples of using try...except
  try:
      result = 10 / 0  # Attempt to divide by zero
  except ZeroDivisionError:
      print("Error: Division by zero!")
  

• except Exception as e: Catches any exception and assigns it to the object e for further processing (such as logging or displaying a message).

  # Catching any exception
  try:
      value = int("abc")
  except Exception as e:
      print(f"An error occurred: {e}")
  

• Multiple except blocks: Allow handling different types of exceptions differently.

  # Handling multiple exception types
  try:
      file = open("non_existent_file.txt", "r")
      content = file.read()
      file.close()
  except FileNotFoundError:
      print("Error: File not found!")
  except IOError:
      print("Input/output error!")
  

• except (...): Combining multiple exception types in one block.

  # Combining exception types
  try:
      some_operation()
  except (ValueError, TypeError):
      print("Value or type error!")
  

• try...except...else: The else block executes if no exceptions occur in the try block.

  # Using else
  try:
      num1 = 10
      num2 = 2
      result = num1 / num2
  except ZeroDivisionError:
      print("Error: Division by zero!")
  else:
      print(f"Division result: {result}")
  

• try...except...finally: The finally block always executes, regardless of whether an exception occurred or not. It is used for resource cleanup (e.g., closing files).

  # Using finally
  file = None
  try:
      file = open("data.txt", "r")
      content = file.read()
  except FileNotFoundError:
      print("File not found.")
  finally:
      if file:
          file.close()
          print("File closed.")
  

• raise: Allows explicitly raising an exception.

  # Explicitly raising an exception
  def validate_age(age):
      if age < 0:
          raise ValueError("Age cannot be negative!")
      return age
  
  try:
      validate_age(-5)
  except ValueError as e:
      print(f"Validation error: {e}")