Exception handling lets your program gracefully manage errors and unexpected situations, instead of crashing abruptly.

Basic exception handling structure:

The core structure of exception handling in Python involves try, except, else, and finally blocks.

try:
  # code that might raise exceptions
except FirstException as e:
  # code to handle FirstException
except SecondException as e:
  # code to handle SecondException
except Exception as e:
  # code to handle any other exception
else:
  # code to execute if no exception was raised
finally:
  # code to execute no matter what (exception or not)

Basic exception handling example:

def divide(i, j):
  try:
    d = i / j
  except ZeroDivisionError as e:
    print(f'ZeroDivisionError: {e}')
    return None
  except TypeError as e:
    print(f'TypeError: {e}')
    return None
  else:
    print(d)
    return d
  finally:
    print('done')

divide(2, 1) # correct division
divide(2, 0) # zero division
divide(2, 'a') # type error

Output:

2.0
done
ZeroDivisionError: division by zero
done
TypeError: unsupported operand type(s) for /: 'int' and 'str'
done

Failing silently:

try:
  i = 1 / 0
except ZeroDivisionError:
  pass # special statement that tells python to swallow the exception

Custom exception class example:

class CustomZeroDivisionError(ZeroDivisionError):
    """Custom exception for zero division errors."""
    def __init__(self, message, dividend=None, divisor=None):
        super().__init__(message + f" | dividend:{dividend}, divisor:{divisor}")

try:
  raise CustomZeroDivisionError('division by zero', 1, 0)
except CustomZeroDivisionError as e:
  print(e)

Output:

division by zero | dividend:1, divisor:0