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Please explain this Python code

list = ['a', 'b', 'c'] list += 'de' print (list) The output is ['a', 'b', 'c', 'd', 'e'] Why Not?🤔 ['a', 'b', 'c', 'de']

2/26/2021 6:30:57 AM


9 Answers

New Answer


'+' Operator applied to list objects is used to concatenate lists. When you concatenate a list obj with a str objects, the str objects will get internally converted to list, which results in list(de) # ['d', 'e']. Thats why your code is behaving so. You will get your expected result, when you use list.append('de')


Use two characters d and e separately


I realized that I have got 3 dislikes on my answer. That is weird. Maybe I have to explain a little bit more... I said that list += 'de' is equivalent to : list.extend('de') This is not *totally* right list += 'de' Is in fact equivalent to : list = list.__iadd__('de') (of course, if we don't look further at the bytecode, because we can see that it is not *strictly* equivalent) And here is a probable implementation of __iadd__ on lists: def __iadd__(self, obj): self.extend(obj) return self So it is *quite* equivalent to: list.extend('de')


You should make another list = ['de'] and add it to your list to get the second result Python convert str char to individual element list. So the reason .


If you add a string to the list, Python will add each letter separately in the list. If you like to add the whole word, you have to use "append" method to do this.



they are srtings so they are indexed that why they have there own indexs you should append de if you want your output to be [a,b,c,de]


Following up on what G B said, you will get your expected result with list = ['a', 'b', 'c'] list += ['de'] print (list)


list += 'de' Is equivalent to : list.extend('de')