Python - Multiple Except Blocks

The way of handling an exception varies from one exception type to another.

Therefore, for every exception type, a separate except block can be provided.

Python allows multiple except blocks with a single try block. This is recommended whenever different exceptions require different handling logic.

D:\Python_classes>py test.py

Enter First Number: 10
Enter Second Number: 2

5.0

D:\Python_classes>py test.py

Enter First Number: 10
Enter Second Number: 0

Can't Divide with Zero

D:\Python_classes>py test.py

Enter First Number: 10
Enter Second Number: ten

please provide int value only

• With the input 10 and 2, no exception occurs and 5.0 is printed.
• With 10 and 0, a ZeroDivisionError is raised, so the except ZeroDivisionError block runs.
• With 10 and ten, a ValueError is raised, so the except ValueError block runs.

1. A single try block can have multiple except blocks.
2. Each except block handles a specific exception type.
3. Only one matching except block executes for a raised exception.
4. If no exception occurs, none of the except blocks execute.

If multiple except blocks are available, the order of these blocks is very important.

The Python Interpreter always checks the except blocks from top to bottom until it finds the first matching exception handler.

Once a matching except block is found, Python executes that block and ignores the remaining except blocks.

Output for input 10 and 0:

ZeroDivisionError is a child class of ArithmeticError.

Python checks the except blocks from top to bottom. Since ZeroDivisionError matches ArithmeticError first, the except ArithmeticError block runs.

The except ZeroDivisionError block is never executed, because the first matching block wins.

Sometimes the same handling code is required for multiple exception types.

Instead of writing separate except blocks for every exception, Python allows us to write a single except block that can handle multiple different exception types.

This approach reduces code duplication and makes programs easier to maintain.

• Parentheses () are mandatory while specifying multiple exception classes.
• Internally, Python treats this group of exception classes as a tuple.
• If any one of the listed exceptions occurs, the same except block executes.

Output 1 - input 10 and 0:

division by zero

Output 2 - input 10 and ten:

invalid literal for int() with base 10: 'ten'

If a ZeroDivisionError occurs, the block handles it and the exception object msg contains division by zero.

If a ValueError occurs, the same block executes and msg contains the corresponding description.

Thus, one except block can handle multiple exception types.

1. Reduces duplicate exception handling code.
2. Makes programs cleaner and easier to read.
3. Improves maintainability.
4. Useful when multiple exceptions require the same handling logic.
5. Supports printing the exception description using the exception object.