all Python 3Loopsconstruct

for

for loop

A loop over the items of an iterable. It runs the loop body for every item: of a list, a string, a range, a dictionary and so on.

Syntax

for переменная in итерируемое:
    блок

The loop variable does not vanish when the loop ends — it keeps its last value and stays visible in the surrounding code. The other common trap is mutating a list (adding or removing items) while iterating over it: the iteration goes wrong, so walk over a copy or build a new list instead.

Examples

for x in [1, 2, 3]:
    print(x, end=" ")  # → 1 2 3

for ch in "abc":
    print(ch, end="")  # → abc

for i in range(5):
    print(i, end=" ")  # → 0 1 2 3 4

d = {"a": 1, "b": 2}
for k, v in d.items():
    print(f"{k}:{v}", end=" ")  # → a:1 b:2

for i, val in enumerate(["x", "y", "z"], start=1):
    print(f"{i}.{val}", end=" ")  # → 1.x 2.y 3.z

for a, b in zip([1, 2], [10, 20]):
    print(a + b, end=" ")  # → 11 22

See also

Common errors

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