Exception_Handling.md

Exception Handling (try,except,else,finally & Raise)

• Exception handling allows your programs to recovr from errors gracefulls, by using the 4 below we can detect potential issues and build better applications.

1. Try code example

python
try:
  x = 10/0
except ZeroDivisionErroe:
  print("You can't divide by zero!")

try: the block of error where the programmer suspects an error might occur

except: this block only runs if the specified type error is raised inside the try

ZeroDivisionError: the error caught & handled

2. Except

python
try:
  x = 10/2
except ZeroDivisionError:
  print("Division by zero ! ERROR!")
else:
  print("Sucessfull division" , x )
finally:
  Print("This bloxk will always run!")

3. Else & Finally

else: runs only if not exception raised in the try box

finally : will always run ; useful for clean-up tasks (closing files or releasing resources)

4. Catching multiple errors with except

• Using the exception object, aliased to another name with the *as keyword.

• here we're using e as an alias for the error object.

  try:
     x = 1/0
  except ZeroDivisionError as e:
    print(f'Error occured : {e}')
  

• using *e lets you access the actual error message

  *4.1

  • To catch multiple exceptions in a single except clause by specifying the exceptions as a tupl:

    try:
      number = int(input('Enter a number: '))
      result = 10 / number
    except (ValueError, ZeroDivisionError) as e :
      print(f'Error occurred: {e}')
    

Raise Statements

• raise statements allows triggering a manual exception in your code; gives programmer the control over when and how the errors are generated.
• raise statements are mainly used to throw an exception at any point in your program
• here are one of many examples how Python's raise statements could be used

def chech_age(age):
  if age < 0 :
    raise ValueError('Age cannot be negative') 
  return age
try:
  check_age(-5(
except ValueError as e :
  print(f'Error : {e} ') # Error age cannot be neg

• in this code raise is the keyword which triggers the exception

• here we're raising a value Error with a custem message when in invalide age is provided

• re raising the current exception using the raise statement is particularly useful in exception handling

  def process_data(data):
      try:
          result = int(data)
          return result * 2
      except ValueError:
          print('Logging : Invalide data received ')
          raise  #Re-raises the same ValueError
  try:
      process_data('abc')
  except ValueError:
      print('Handled at higher level')
  

  • the keyword raise (without arguements) is re-raising the current exception.This allows to log or perform cleanup while still propagating the error up the call stack.