CODEWITHSUNDEEP
pythonlistloops
user9121250
user9121250

Reputation:

Why am I getting this output

In the mentioned code I expect output as 0 1 2 3, but I got an output which is 0 1 2 2.Please help me why it is so? , how it is working.This is the code of my problem statement.

a = [0, 1, 2, 3]
for a[-1] in a:
    print(a[-1])

This is code in python, output got is 0 1 2 2

Upvotes: 1

Views: 170

Answers (2)

Vicrobot
Vicrobot

Reputation: 3988

What you're doing is this:

>>> for i in a:
...     a[-1] = i
...     print(a[-1])
... 
0
1
2
2

Its because a[-1] is assigned the value of next(iterable a) in a sense, at each loop. for loop makes iterable, then calls next on that iterable, then it's assigned to the iteration variable.

Upvotes: 1

Max Kaha
Max Kaha

Reputation: 922

In this case you are reassigning the values inside your list whilst iterating over it. If you print out the entire list in your loop you will see the following:

>>> for a[-1] in a:
...   print(a)
...
[0, 1, 2, 0]
[0, 1, 2, 1]
[0, 1, 2, 2]
[0, 1, 2, 2]

If you want to go through individual items in your list you would have to name your variable a different way such as:

for item in a:
    print(item)

Output then is 0 1 2 3 as you would expect.

Upvotes: 4

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