String slicing

[bowlofred]

# my question is that why second one is showing a output ( if you say that slicing includes the start index then what happened with the var1 output it is also starting with the same index)

The second index must be "beyond" the first index to show anything. In other words, it must lie in the correct step direction from the first index..

In your first instance, you are stepping forward (step = 1), but the second index is rearward (-16 is more rearward than -1). Because of this, no portion is selected.

In the second case, you are stepping forward again, but now 16 is beyond -1 (the last index of the string is 14). So displaying index 14 (same as index -1) is allowed.

These are all equivalent

# First index is in range, second index is in step direction.
>>> str1[14:100]
'i'
>>> str1[-1:100]
'i'

And these are equivalent

# First index is in range, second index is not in step direction.
>>> str1[14:1]
''
>>> str1[14:-16]
''
>>> str1[-1:-16]
''