What's the output of this code and explain. a=[1,2,3,4] for a[-1] in a: print(a[-1])

Question

What's the output of this code and explain.

a=[1,2,3,4]
for a[-1] in a:
print(a[-1])

Answer 1

If you copied your question from stackoverflow, you definitely know the answer.
Anyway, for those who don't know.

https://stackoverflow.com/questions/35046497/weird-for-loop-statement

Answer 2

Amir's link explains all there's to explain but I think this being an assignment needs emphasis, because if you think of it as an equality that causes problems.

"for x in somelist" starts with:

x = somelist[0]

Left of the assignment is the variable, right of the assignment is the value assigned to the variable on left.

So substituting, you get

a[-1] = a[0]

so a[-1] is reassigned the value a[0] which is 1.

Rinse and repeat you get the whole output you posted. (edit: Felix posted)

There was a similar question a while back asked about dictionary, answered by Jayakrishna.

https://www.sololearn.com/Discuss/3043254/?ref=app

In short it's the position of a[-1] in the for loop that makes it the variable part of an assignment by that loop, and assignment is not the same thing as equality.

Answer 3

The Output of that Code's:
1
2
3
3
I can't really explain why it's like that or what happens, but maybe tipping, can help you understand what happens there:
a=[1,2,3,4]
for a[-1] in a:
print(a)

Answer 4

I can't figure out the logic either.

I can see the outputs generated by playing with the code, but the logic behind it eludes me