What is the output of the code?Also tell how?

Question

A=[1,2,3,4,1]
for i in A:
A[i]=0
print(A)

Answer 1

Devendra Yadav and others in this discussion :

Hi,

At this code we use a "for" loop on a list, for loop in python works as "foreach" loop in other programing languages.

Therefore, this loop takes one by one the members of the list, not their indexes.

So:
Step by step: #A is:[1,2,3,4,1]

1⃣
for i in A: #i=1
A[1]=0 #result: A is: [1,0,3,4,1]

2⃣
for i in A: #i=0
A[0]=0 #result: A is: [0,0,3,4,1]

3⃣
for i in A: #i=3
A[3]=0 #result: A is: [0,0,3,0,1]

4⃣
for i in A: #i=1
A[1]=0 #result: A is: [0,0,3,0,1]

As you can see, index 2 and 4 are ignored because our list does not include these numbers and therefore the for loop could not access to Their corresponding indexes in the list.

I edit your code here, run it and if my answer and my code were useful, pls. Upvote them. 😍

https://code.sololearn.com/cJOd6jLNQy4P/?ref=app

Answer 2

Correct code is:

A=[1,2,3,4,1]
for i in range(len(A)):
A[i]=0
print(A)

Run in code playground :

https://code.sololearn.com/cJOd6jLNQy4P/?ref=app

Answer 3

I think in this loop every element in the array is set a value 0. So after loop the array is A = [0, 0, 0, 0, 0].

Answer 4

Ok, interesting.

Answer 5

‌‌ ‌ Thank u, Now I got the logic😊

Answer 6

D⚽⚽⚽⚽7⃣7⃣7⃣
No buddy, answer is [0,0,3,0,1] but don't know how.

Answer 7

It starts from the first element and changes index 1 which is number 2 to 0

Now it takes the second element which it just last time assigned from 2 to 0 so it changes the first element which is number 1 to 0

Now it changes index 3 which is number 4 to 0

Then it takes the second last element which was 4 but it changed it to zero so it changes the first element.

Because numbers 2 and 4 was changed before it looped them number 3 and 1 remains the same.

Answer 8

Toni Isotalo thanks 😊

Answer 9

I think the main thing that catches folks on this one is thinking that 'i' in the for loop would refer to the index (0-4) whereas it is the value of each item in the sequence even as they are being updated.

A fun experiment is to see the difference in this small change:

A = [1, 2, 3, 4, 1]
for i in list(A):
A[i] = 0
print(A)

Answer 10

https://www.sololearn.com/Discuss/1353515/?ref=app
Similar logic