Module 4 · Exceptions · Lesson 4 of 6

Exceptions you'll meet

Python has dozens of built-in exception types, but a handful show up again and again. Recognising them on sight turns a scary traceback into a quick diagnosis — you read the name and you already know roughly what happened.

• ZeroDivisionError — any division by zero, with /, // or %.
• ValueError — the right type but an impossible value, like int("abc").
• TypeError — the wrong type for the operation, like adding a string to a number.
• AttributeError — asking for a method or attribute a value doesn't have.

You can capture the exception object itself with except ... as e, which is handy for printing its message. Run this to see four different exceptions, each caught and named:

Notice the single except Exception caught all four. That's because these specific errors are all kinds of Exception — so catching the general type catches the specific ones too. (One to leave alone: SyntaxError means your code itself is malformed — fix it, don't catch it.)