Why cant i negative slice my value?

Question

Guys im trying to negative slicing the string "Hello" but the output is just a blank space like nothing at all. But if i do the normal slicing it will just work fine. How? HELP!!
This worked
a = "Hello"
print(a[0:3])
output -> Hel
This didnt!
a = "Hello"
print(a[-1:-3])
output -> nothing
i want it to print
ll
how? Help!!

Answer 1

No output because end (-3) comes before start (-1).
If you want output you can:
- swap start and end (a[-3:-1])
- instruct the interpreter to go backwards (a[-1:-3:-1])

Answer 2

Take a look here, it's all explained.https://www.sololearn.com/learn/JUMP_LINK__&&__Python__&&__JUMP_LINK/2453/?ref=app

Answer 3

print(a[-1::-3])
there are tow colon(:)

Answer 4

why do you need to put two colon?

Answer 5

Every number express about indexes
First number : determind which number starting from it
Second number Explains how many will pass to the last number and the default is 1
Last number : The last number is not printed, but the number that precedes or is subtracted from index number 1 so that we know we will print to any number