reversed() Reverse sequence
Last updated: 2026-09-22
reversed() Reverse sequence
reversed(seq) returns a reverse iterator; works on list, tuple, str, range, etc.
| Category | Built-in Functions |
|---|---|
| Kind | Built-in Function |
| Python Version | all |
📝 Syntax
reversed(sequence)⚙️ Parameters
| sequence Required | A sequence (list/tuple/str/range, etc.) or an object implementing __reversed__. |
|---|
Returns：A reverse iterator usable with list() or a for-loop.
💥 Raises
TypeError— Raised when the object is not a sequence and has no __reversed__.
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
[3, 2, 1]
o l l e h🏷️ Related Built-in Functions
💡 Related Cases
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❓ FAQ
QWhat does reversed() return?
AIt returns a reverse iterator, so you need list(reversed([1, 2, 3])) to get [3, 2, 1]; it is not itself a list.
QWhat is the difference between reversed() and lst[::-1]?
Alst[::-1] returns a new complete list (copying the data, O(n) memory); reversed(lst) is a lazy iterator that copies nothing and is only suitable for traversing once from end to start.
QWhy does reversed({1, 2, 3}) raise a TypeError?
AA set is unordered and has no concept of 'reversal'; reversed() only supports sequences (list/tuple/str/range) or objects implementing __reversed__.
QAre reversed() and sorted(lst, reverse=True) the same?
ANo. reversed keeps the original order and outputs it backwards without sorting; sorted(reverse=True) sorts in descending order. For [3,1,2], the former gives [2,1,3] and the latter [3,2,1].
