How do I iterate over a list in reverse order?

Question

Without touching the original/initial list.

Answer 1

suppose original list is
a=[1,2,3]
b=a
Now
for i in b[::-1]:

Answer 2

If you mean looping through a list in reverse, use:
for x in reversed(range(len(list))):

Answer 3

I see that you uused the word iterate,, but try this:
nums =[9,6,5,8]
Print(*nums[::-1], sep="\n")

Output:
8
5
6
9

Answer 4

Abhay Why bother with the copy at all?

Answer 5

If you want to iterate a list in reverse without having to create a temp copy of the list, you can use the following options in this code:

https://code.sololearn.com/cgz3QnsBd8Nf/

NOTE: Using list comprehensions / slicing will create a temp copy of the list.

Answer 6

Adding to the answer I provided before that won't work if you make changes to list b
In example
a=[1,2,3,4]
b=a

For i in b[::-1]:

If you perform some operations on b that will be applied to a as well so the best would be to store a shallowcopy of a into b like

b=a[:]

now any changes made to b won't change the original list a

Answer 7

David Carroll questions says without touching the original list so for that you need to make a copy if i am not wrong!

Answer 8

Abhay Ah... I think we both read that question with different interpretations. 😉

You interpreted "without touching the original/initial list" as not _referencing_ the original list. That actually makes sense to me now.

I interpreted it to mean without _modifying_ the original list.

The problem is the use of the word "touching" makes this question ambiguous as both interpretations are valid.

Thanks for clarifying. 😉👌

Answer 9

"Without touching"....do you mean..."...without changing the order of the original list?
...if so...just do:-
a=[1,2,3]
for i in a[::-1]:
print(i)
print(a).....# for comparison.

Answer 10

Use "reversed" keyword

Answer 11

See the code in my profile.