String slicing in Python for string reversal-CodePudding

I want to reverse a string using slicing and initially I tried

string = "abcdef" 
print(string[len(string) - 1: 0: -1])

However this only prints up to the index 1

fedcb

So, I decided to change the slicing by changing the ending index of the slicing to -1

string = "abcdef" 
print(string[len(string) - 1: -1: -1])

I'm assuming this will print up to index 0. But this did not print any characters of the string upon running. My question is why doesn't this work?

CodePudding user response：

for your question,

string = "abcdef" 
print(string[len(string) - 1: -1: -1])

returns an empty string since it's taking the second argument as the stopping point : which is exactly the last character that's why it's empty ,

you can test it by running :

    string = "abcdef" 
    print(string[len(string) - 1: -2: -1])

it only returns the character 'f' xhich is the last character .

Now for what you're trying to achieve : you can either use :

string = "abcdef" 
print(string[-1: -len(string)-1: -1])
##or 
print(string[::-1])

CodePudding user response：

from the docs slice:

 class slice(start, stop[, step])

Return a slice object representing the set of indices specified by range(start, stop, step). The start and step arguments default to None.

you can use the [::-1] index to do that

>>> s = 'hello'
>>> s[::-1]
'olleh'

with a negative step, the index will go from -1 to ~(len(s)-1), and by that I mean that the string will go from index -1 to 0 reversed

CodePudding user response：

this is what your looking for

string = "abcdef"
print(string[::-1])