HTML
JAVASCRIPT
CSS
PYTHON

Python Error Handling

Python Error Handling

Error handling in Python is the process of managing errors or exceptions that arise during the execution of a program. Proper error handling ensures your program runs smoothly and fails gracefully when unexpected conditions occur.

Key Concepts in Python Error Handling

  • Exceptions: Exceptions are runtime errors that disrupt the normal flow of a program. Common exceptions include:

    • ZeroDivisionError
    • FileNotFoundError
    • ValueError
    • TypeError

  • try and except:

    • The try block contains code that might raise an exception.
    • The except block catches and handles the exception.

  • else: Executes code if no exceptions occur in the try block.

  • finally: Executes code regardless of whether an exception was raised or not.

  • Raising Exceptions: You can explicitly raise exceptions using the raise statement.

  • Custom Exceptions: You can define your own exceptions by creating a class derived from the Exception class.

    • Syntax and Examples

    1. Basic try and except

      try:
      num = int(input("Enter a number: "))
      result = 10 / num
      print(f"Result: {result}")
  except ZeroDivisionError:
      print("Error: You cannot divide by zero.")
  except ValueError:
      print("Error: Invalid input. Please enter a number.")

    2. Using else

      try:
      num = int(input("Enter a number: "))
      result = 10 / num
  except ZeroDivisionError:
      print("Error: You cannot divide by zero.")
  else:
      print(f"Result: {result}")

    3. Using finally

      try:
      file = open("example.txt", "r")
      content = file.read()
      print(content)
  except FileNotFoundError:
      print("Error: File not found.")
  finally:
      print("Execution completed, cleaning up...")

    4. Raising Exceptions

      def check_positive(number):
  if number < 0:
          raise ValueError("The number must be positive.")
      return number

  try:
      print(check_positive(-5))
  except ValueError as e:
      print(f"Error: {e}")

    5. Creating Custom Exceptions

      class CustomError(Exception):
      pass

  def check_condition(value):
      if value != "expected":
          raise CustomError("Unexpected value provided!")

  try:
      check_condition("unexpected")
  except CustomError as e:
      print(f"Caught a custom exception: {e}")

    Explanation of Each Block

    • try: Protects the code that might cause an exception.
    • except: Specifies how to handle specific exceptions.
    • else: Executes if no exceptions are raised in the try block.
    • finally: Ensures that clean-up code runs, like closing files or releasing resources.

      • Best Practices

      • Be specific in exception handling to avoid masking unintended errors. 
          except (ValueError, TypeError):  # Catch specific exceptions
      • Avoid using a bare except: as it catches all exceptions, including SystemExit and KeyboardInterrupt.
      • Always clean up resources using finally or context managers. 
          with open("example.txt", "r") as file:
    content = file.read()

      By mastering error handling, you can make your Python programs more robust and user-friendly!

Previous