Struked in a question.Someone can explain what happen here.

Question

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

Output seems to be 0 1 2 2

Answer 1

In each iteration, the last item of 'a', i.e. a[-1] is copied with values from 'a' iterable. So we have different 'a' in each iteration. If we want to see 'a' in each step we'll have:
1. [0,1,2,0] => a [-1]=0
2. [0,1,2,1] => a [-1]=1
3. [0,1,2,2] => a [-1]=2
4. [0,1,2,2] => a [-1]=2

Answer 2

Qasem Shouldn't the fourth iteration be [0,1,2,3] as 3 is in a and hence a[-1] as 3

Answer 3

Qasem Thanks!! Got it.

Answer 4

Ozair Khan
3 is not in A. It is replaced with 0 at the first iteration and doesn't exist anymore.