PythonDébutant 4 min·Updated: 2026-09-28

How to Reverse a String or List in Python (3 Methods)

Discover idiomatic Python techniques to reverse sequences, complete with time and space complexity trade-offs.

Published by Projet Carthage · Updated 28 September 2026

Concepts & Theory

The slice `sequence[::-1]` creates a reversed copy of a string or list and leaves the original sequence unchanged.

The built-in `reversed()` function returns a lazy reverse iterator. It consumes O(1) auxiliary memory and is optimal when streaming values into a for loop.

For mutable lists, `list.reverse()` performs the inversion in place without allocating extra memory (O(1) space).

Code Example

Try this example

PYTHONPROJET CARTHAGE

# Méthode 1 : Slicing élégant (chaînes & listes)
texte = "Carthage"
inverse = texte[::-1]
print("Slicing :", inverse)  # 'egahtraC'

# Méthode 2 : reversed() puis conversion en liste
mots = ["Python", "IA", "Code"]
print("Itérateur :", list(reversed(mots)))  # ['Code', 'IA', 'Python']

# Méthode 3 : Inversion en place, sans copier la liste
nombres = [1, 2, 3, 4, 5]
nombres.reverse()
print("En place :", nombres)  # [5, 4, 3, 2, 1]

Common Pitfalls & Mistakes

Calling .reverse() on an immutable string

Incorrect / Error

text = "hello"
text.reverse()  # AttributeError

Idiomatic / Correct

text = "hello"
reversed_text = text[::-1]

Strings are immutable in Python. The `.reverse()` method only exists on mutable list objects.

Frequently Asked Questions

Which method is fastest for reversing strings in Python?▾

Slicing is a concise option for producing a copy. Performance depends on your interpreter and data; benchmark your own inputs before choosing an optimisation.

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