Exception Handling with try/except

Sometimes programs crash because of unexpected errors, such as dividing by zero or accessing a file that does not exist.

Instead of crashing, you can use exception handling to deal with errors gracefully.

Python provides four key tools:

• try
• except
• else
• finally

1. try and except

Wrap risky code in a try block. If an error happens, Python jumps to the except block.

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Oops! You can't divide by zero.")

• The division causes an error.
• Python skips the crash and shows a message instead.

2. Handling Multiple Error Types

You can catch different types of exceptions in separate except blocks.

Handling Multiple Error Types

try:
    num = int("abc")
except ValueError:
    print("That's not a valid number.")
except TypeError:
    print("Type mismatch.")

• This handles a ValueError caused by int("abc").

3. else and finally

• else runs only if no error occurs.
• finally runs no matter what, even if there is an error.

else and finally

try:
    value = int("42")
except ValueError:
    print("Conversion failed.")
else:
    print("Conversion succeeded:", value)
finally:
    print("Done checking.")

• else confirms success.
• finally is good for cleanup, such as closing files or connections.

Summary

Keyword	Purpose
try	Run risky code
except	Handle specific errors
else	Runs if no exception occurred
finally	Always runs, used for cleanup

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