The finally block in Python is used in exception handling to define cleanup code that should run no matter what, whether an exception occurred or not.

Why Use finally?

• It ensures important final steps like closing files, releasing resources, or cleanup tasks are always executed.
• It runs whether:
  • An exception occurred
  • No exception occurred
  • An exception was caught or not

Syntax

try:
   # Risky code
except SomeException:
   # Handle error
finally:
   # Always runs

Example 1: finally with No Exception

try:
   x = 10 / 2
except ZeroDivisionError:
   print("Division by zero")
finally:
   print("This always runs")

Output:

This always runs

Example 2: finally with an Exception

try:
   x = 10 / 0
except ZeroDivisionError:
   print("Caught ZeroDivisionError")
finally:
   print("Finally block executed")

Output:

Caught ZeroDivisionError  
Finally block executed

Example 3: No except, Only finally

try:
   x = 1 / 0
finally:
   print("Cleanup code")

Output:

Cleanup code  
Traceback (most recent call last):  
 ...  
ZeroDivisionError: division by zero

Explanation:
Even though no except block is present, the finally block still runs before the exception is thrown.

Real-World Example: File Handling

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

Bonus: Combine with finally

try:
   num = int(input("Enter a number: "))
except ValueError:
   print("Invalid input!")
else:
   print("Good job! You entered:", num)
finally:
   print("Execution complete.")

Summary Table