Iterators in Python

An iterator is an object that allows traversal through a sequence of values – one at a time. It's the mechanism behind for loops and many built-in functions.

Python's iteration protocol uses two special methods: __iter__() and __next__(). Understanding iterators helps you create custom iterable objects.

How For Loops Work

for item in iterable: is equivalent to calling iter() and next() repeatedly.

Creating a Custom Iterator

Define __iter__() (returns self) and __next__() (returns next value or raises StopIteration).

Using iter() and next()

Quick Quiz