list.extend() Extend with iterable
Last updated: 2026-09-22
list.extend() Extend with iterable
list.extend(iterable) appends items from iterable; equivalent to lst += list(iterable).
| Category | List Methods |
|---|---|
| Kind | Built-in Type Method |
| Python Version | all |
📝 Syntax
list.extend(iterable)⚙️ Parameters
| iterable Required | An iterable providing the elements (list, tuple, str, ...). |
|---|
Returns：None (appends each item from iterable in place).
Mutates the original：Yes (in place)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
[1, 2, 3, 4]💡 Related Cases
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❓ FAQ
QWhat is the difference between extend() and append()?
Aextend() expands the iterable and adds its items individually; append() adds the object as a single whole. lst.extend([1, 2]) gives [1, 2], while lst.append([1, 2]) gives [[1, 2]].
QWhat does extend('abc') do?
AA string is iterable, so it adds the three characters 'a', 'b', 'c' to the list individually. To add it as a whole use append('abc').
QWhat does extend() return?
ANone; it modifies the list in place.
QWhat is the difference from +=?
AEssentially equivalent: lst += [1, 2] also extends in place (requiring an iterable on the right).
