Python 3.8: for loop goes infinite

Question

I have a list with strings as elements. All of them are in lower case. I want to modify the list so that this list also contains the strings in upper case for the first letter. I wrote this for loop:

> words = ["when", "do", "some", "any"]     
with_title_words = words
> 
>     for u in words:
>         u.title()
>         with_title_words.append(u)
>     print(with_title_words)

When I execute it goes infinite. It outputs all the string elements starting with the capital letter.

You have an infinite loop because you continuously add elements to the loop you're consuming from. `with_title_words = words` does not do a deep copy. It's like a reference. — amiabl, Jun 16 '20 at 10:31
Also, see this answer. https://stackoverflow.com/questions/2612802/how-to-clone-or-copy-a-list/2612990 — Axe319, Jun 16 '20 at 11:07

score 0 · Accepted Answer · answered Jun 16 '20 at 10:24

0

words = ["when", "do", "some", "any"]
with_title_words = words[:]

for word in words:
    with_title_words.append(word.title())

print(with_title_words)

Outputs:

['when', 'do', 'some', 'any', 'When', 'Do', 'Some', 'Any']

or create an empty list word_title_words = [] to add only the titled strings.

answered Jun 16 '20 at 10:24

James

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What does the semicolon mean in word[:]? Never saw that before – t0v4 Jun 16 '20 at 14:04
1

Slice notation. In this example [:] copies the list rather than references it. – James Jun 16 '20 at 15:15

Python 3.8: for loop goes infinite

1 Answers1