Python 中的反向词 function 问题

Question

My code almost works perfectly, with the exception that the first word reversed always 'miss' the last character, the rest of the sentence works fine. Can anyone find the error to debug this code logic?

def reverseWords(str):

    str_len = len(str)
    str = str[str_len-1::-1]

    str_end = ''
    stop = 0
    index = 0

    for i in range(str_len):

        if (str[i] == ' '):
            index = i - 1
            str_end += str[index:stop:-1] + ' '
            stop = i

        elif (i == str_len-1):
            index = i
            str_end += str[index:stop - 1:-1]

    return str_end

print(reverseWords("The greatest victory is that which requires no battle"))
output: battl no requires which that is victory greatest The

Answer 1

A more idiomatic way to do something like this in Python is to split, reverse and join:

def reverse_words(text):
   words = text.split(' ')
   reversed_words = []
   for word in words:
       reversed_words.append(word[::-1])
   reversed_text = ' '.join(text)
   return reversed_text

or, in a single expression,

def reverse_words(text):
    return ' '.join(w[::-1] for w in text.split(' '))

Answer 2

You can not reverse slice the string past its beginning, it's not possible.

Example:

>>>"baby"[3:0:-1]

'yba'

>>>"baby"[3:-1:-1]

''

Answer 3

I think this might be what you are looking for:

reverse = lambda sentence: ' '.join(sentence.split()[::-1])