What is the default stop value for a_list [-1: :-1]?

user_19042642 0
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I have this piece of code:

a_list = [1,2,3,4,5,6]

print (a_list[::-1]) 
print (a_list[-1::-1])
print (a_list[5::-1])
print (a_list[-1:0:-1])

and the output is:

[6, 5, 4, 3, 2, 1]
[6, 5, 4, 3, 2, 1]
[6, 5, 4, 3, 2, 1]
[6, 5, 4, 3, 2]

Because step size is negative, the default start is at 5 or -1 index, so the first three statements give the same output. But when I was trying to figure out what the stopping point is I tried print (a_list[-1:0:-1]) and it obviously excludes the value at 0 index which is 1. also, the index before 0 is -1, and because it's the same as the starting point it gives an empty list. So my question is, what is the default stop point for a_list [ : :-1]? Or more generally, what is the default for any_list[start:stop:step] with a negative step size?

slice python-3.x list python
1 Answers

When explicitly defined, the stop is excluded.

So in your first three example all remaining values are used, however in the last one (a_list[-1:0:-1]), 0 is excluded.

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