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Looping one step too far
🐛 Fix the bug Topic: lists Difficulty: easy Free
What this problem practises
Lists are mutable and assigned by reference. That one fact explains most list bugs: aliasing between what look like "copies", append() and sort() returning None, and slice boundaries that disagree with the index arithmetic.
This is a fix-the-bug problem: a short program is given in its broken state, and the task is to repair the code so it produces the required output. The interactive editor runs your fixed version in the browser and checks it for you — no setup, no local interpreter.
Difficulty: easy — the fix or the trick is normally a single line, and a careful read should be enough.
The challenge
This should print every item in the list, but crashes partway through. Fix it.
The code runs in PyDebug’s in-browser compiler. Open the problem, run the snippet, watch the exact error or output, and keep iterating until it is right. Signed-in solves count toward XP and your daily streak.
The error it raises
Run the broken snippet and Python stops with this exact error: IndexError: list index out of range. Match it to the Python errors guide, then repair the line that produced it — knowing the message is half the fix.
The snippet
The interactive editor pre-fills exactly this code, broken and ready to repair:
fruits = ["apple", "banana", "cherry"]
for i in range(4):
print(fruits[i])More lists problems
- List slicing with step medium
- in operator on a list easy
- List copy vs reference easy
Keep going
- Python debugging guide — a systematic method for finding bugs like this one fast.
- Browse every lists problem in this topic.
- Common Python errors and what they actually mean, plus the Python glossary for any term used on this page.