Day 7: Using list.sort() incorrectly

 

🐍 Python Mistakes Everyone Makes ❌

Day 7: Using list.sort() Incorrectly

Sorting lists in Python looks simple, but there’s a subtle behavior that often confuses beginners.

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❌ The Mistake

numbers = [3, 1, 2]

sorted_numbers = numbers.sort()
print(sorted_numbers)

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❌ Why this fails?

Because list.sort() sorts the list in place and returns None.

• The original list gets sorted

• No new list is returned

So sorted_numbers becomes None.

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✅ The Correct Way

numbers = [3, 1, 2]
numbers.sort()
print(numbers)

This modifies the original list and works as expected.

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🧠 Simple Rule to Remember

• list.sort() → sorts in place, returns None

• sorted() → returns a new sorted list

Example:

numbers = [3, 1, 2]
sorted_numbers = sorted(numbers)
print(sorted_numbers)

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✅ Key Takeaway

If you need a new sorted list, use sorted().
If you want to modify the existing list, use list.sort().