Can someone explain this for me, I don't understand why? or how? the answer is 8.

Question

list = [1,1,2,3,5,8,13]
print(list[list[4]]

Result: 8

Answer 1

Besides all of these things, I would like to mention something else:

▪︎the code that was initially shown has an issue, since:

print(list[list[4]]

a round closing bracket is missing at the end of the line

▪︎an other issue that the identifyer name <list> should not be used, as there is a class and a function in python with the same name. This will overwrite the existing class. here is an example that demonstrates what happens if this fact is ignored:

#list = [1,1,2,3,5,8,13]
#print(list[list[4]])
print(list('abcd')) # result is normally ['a', 'b', 'c', 'd']

▪︎first try: run this code as it is, so the result will be ['a', 'b', 'c', 'd']
▪︎second try: remove the <#> from line 1 and 2, and run the code again
▪︎the result will be a error message:

《 TypeError: 'list' object is not callable 》

the end of the story is, that this issue might not raise an error during developing or testing a code, but can appear when using the app. to catch this bug can be a real nightmare.

Answer 2

First inner list is evaluated which returns 5 , now that value 5 act as an index for outer list .

list[list[4]] is reduced to list[5] which returns 8 not 4.

Answer 3

Will Lim you forgot to edit your question as well .

Answer 4

Will Lim

list[3] == 3
so list[list[3]] == list[3] == 3

list[4] == 5
so list[list[4]] == list[5] == 8

Answer 5

Finally I understand. Thanks visph Lothar Abhay .

Answer 6

Abhay OP just have edited its description ;P

Answer 7

Abhay :D

I even didn't noticed that point (passing my way while seeing your answer) ;P

Answer 8

Abhay Sorry for editing the question, now can explain one more time more clearly cause I'm still don't understand.

Answer 9

Will Lim don't forgot that indices start at zero (list[0] is the first item) ;)

Answer 10

visph yes but I try to change list[list [4]] to list[list[3]] the result is 3 not 5, if as what yours mention above the result should be 5 but why I get 3

Answer 11

first list [4] will result in 5 so list [5] will give you op 8

Answer 12

We know that list[4] is 5
and then the program says list[list[4]]
Thats the same thing as saying list[5]

list[5] is 8

Thats my answer, hope u can use ir ;)