-3
data = [2, 4, 3, 1, 5, 10, 9]

data.pop()
print(data)

result: [2, 4, 3, 1, 5, 10]

the above is what i think makes sense

however,

data = [2, 4, 3, 1, 5, 10, 9]

Print(data.pop())

I got this

Result : 9

what is the difference?

Mark
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어남영
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    It's worth look [at the docs](https://docs.python.org/3/tutorial/datastructures.html). `pop()` alters the original list and *returns* the value. In one case you are printing the altered list, in the other you are printing the returned value. – Mark Dec 23 '20 at 04:28

3 Answers3

1

In the 1st situation, you are printing a list of data. I have re-lined the code and added comments to make it more understandable:

Scenario 1:

data = [2, 4, 3, 1, 5, 10, 9] # the given data list
data.pop() # pop the last element off the list
print(data) # print 'data' (which is the list)

The reason why the result here is [2, 4, 3, 1, 5, 10] is because you are popping from the list, and then printing the list itself.

Scenario 2:

data = [2, 4, 3, 1, 5, 10, 9] # the given data list
print(data.pop()) # print the value returned by data.pop(), which is 9

# Result : 9

List.pop() is a method that returns the popped value from the list. So, by doing print(data.pop()), you are requesting to print the single popped value rather than the data list in its entirety.

See the Python documentation on the List.pop() method here.

Paul
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0

The pop() method returns the value which was deleted from the list. If you try to print that d.pop() it just returns the removed value.

Nanthakumar J J
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When you use pop( ) it returns the last element of the list and internally it deletes last element from the list.

Note that in the first code you’re printing data ( the list ) and in the second one you’re printing what pop returns

Juan José Hoyos Urcué
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