all Python 3Built-in functionsterm

next

iterators

Returns the next item of an iterator. default is returned if the iterator is exhausted.

Syntax

next(iterator[, default])

next takes an iterator, not a container: next([1, 2, 3]) is a TypeError — wrap the list in iter() first. Without the second argument an exhausted iterator raises StopIteration, so either catch it or pass a default. Inside a generator this matters even more: an unhandled StopIteration is converted into RuntimeError (PEP 479), which hides where the problem actually came from.

Examples

it = iter([1,2,3])
print(next(it))  # → 1
print(next(it))  # → 2
print(next(it))  # → 3
print(next(it, 'end'))  # → end
g = (x**2 for x in range(5))
print(next(g), next(g))  # → 0 1

See also

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