IndexError while printing a list

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 program should print 2, 13, 23 (one per line) but crashes with IndexError on the last step. Fix the loop range.

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 snippet

The interactive editor pre-fills exactly this code, broken and ready to repair:

nums = [2, 13, 23]
for i in range(len(nums) + 1):
    print(nums[i])

More problems

• List slicing and indexing easy
• List slicing and indexing easy
• break vs continue medium

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.