Does "IndexError: list index out of range" when trying to access the N'th item mean that my list has less than N items?

Question

I'm telling my program to print out line 53 of an output. Is this error telling me that there aren't that many lines and therefore can not print it out?

Answer 1

If you have a list with 53 items, the last one is thelist[52] because indexing starts at 0.

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From Real Python: Understanding the Python Traceback - IndexError:

IndexError

The IndexError is raised when you attempt to retrieve an index from a sequence, like a list or a tuple, and the index isn’t found in the sequence. The Python documentation defines when this exception is raised:

Raised when a sequence subscript is out of range. (Source)

Here’s an example that raises the IndexError:

test = list(range(53))
test[53]

---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-6-7879607f7f36> in <module>
      1 test = list(range(53))
----> 2 test[53]

IndexError: list index out of range

The error message line for an IndexError doesn’t give you great information. You can see that you have a sequence reference that is out of range and what the type of the sequence is, a list in this case. That information, combined with the rest of the traceback, is usually enough to help you quickly identify how to fix the issue.