Python Challenge Problem

Question

I am confusing with this code.
a = [1,2,3,4,5]
for a[-1] in a:
print(a[-1])
#How to explain this output?
'''
1
2
3
4
4
'''
https://code.sololearn.com/cTD1wuLKrMg0/?ref=app

Answer 1

During the execution of this code 2 main things happen:
1. Treating a[-1] as a variable of for loop.
2. Multiple assignment of the last element of list( a ) i.e 5. Expressed by a[-1]

See statement.( for a[-1] in a ). In the 1st execution it assigns a[-1] .i.e 5 to 1 ( a[ -1 ] = 1 ), then the loop prints a[ -1 ] treating it a loop variable assigned to 1st element of list a. Therefore variable a[-1] prints 1.

These two things continue and when the loop reaches at 4 just before last element. The list looks like [1,2,3,4,3] that follows:

👉 a[ -1 ] as an index. That reads a[ -1 ] = 4("3 = 4" means last element assigned to 4 because the loop is in 4th element)

👉 And a[ -1 ] as a variable of for loop (here loop is in 4th element therefore the variable is equals to 4). And so it prints 4.

Now the list looks something like this
[1,2,3,4,4]

In last execution the index a[ -1 ] = 4 i.e 4 is assigned to 4. And so the variable a[ -1 ] is printed which is 4.

I tried my best to make is understandable.👍

Answer 2

This is absolutely terrible questions 😭😭.

Answer 3

I hate it.

Answer 4

Hey PythonPip your explain is the easist to understand it. Thanks for sharing your thought. I have the blast to coding.