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If I write my code like this,

friends = ["Kafi", "Saif", "Shaheer", "Azmain", "Labid", "Faiz", "Azmain"]

lucky_numbers = [114, 151, 172, 7, 1, 63, 14, 543]

friends.extend(lucky_numbers)

print(friends)

then my code runs perfectly. But if I use the extend function inside the print function like this,

friends = ["Kafi", "Saif", "Shaheer", "Azmain", "Labid", "Faiz", "Azmain"]

lucky_numbers = [114, 151, 172, 7, 1, 63, 14, 543]

print(friends.extend(lucky_numbers))

then I get "None" as an output. Why can't I use the extend function inside the print function?

tryingtobeastoic
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2 Answers2

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extend is in-place function that returns nothing. Printing output from a function that hasn't returned anything will give you None if you don't want to change friends then make a copy of it

newfriends = friends.copy()
newfriends.extend(lucky_numbers)
print(newfriends)
Kuldeep Singh Sidhu
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1

Your print statement prints the return of friends.extend(lucky_numbers), which is None. From the docs:

array.extend(iterable) - Append items from iterable to the end of the array.

So extend() changes the array it is called on, but it doesnt return anything, ergo there is nothing to print.

Chrissu
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