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Detailed explanation of Python string processing examples

零下一度
零下一度Original
2017-06-16 10:33:291415browse

This article mainly introduces in detail the method of word reversal in Python string processing, which has certain reference value. Interested friends can refer to

Python String Processing Learning , there is a simple but classic question, which is to reverse the string according to the words and retain the original spaces:
For example: ' I love China! '
Convert to: ' China! love I '

Two solutions:

Solution 1: Traverse the string from front to back. If the first one is a space, skip it directly , until the first character that is not a space, if it is a separate letter, skip it as well, otherwise, reverse the word, traverse backward, and finally use the reserve method to print the entire string from back to front.

Option 2: Directly use the re (regularization) package for inversion

The code is as follows:


import re

def reserve(str_list, start, end):
  while start <= end:
    str_list[start], str_list[end] = str_list[end], str_list[start]
    end -= 1
    start += 1

str = &#39; I love china!  &#39;
str_list = list(str)
print(str_list)
i = 0
print(len(str_list))

# 从前往后遍历list,如果碰到空格,就调用反转函数,不考虑单个字符情况
while i < len(str_list):
  if str_list[i] != &#39; &#39;:
    start = i
    end = start + 1
    print(end)
    while (end < len(str_list)) and (str_list[end]!=&#39; &#39;):
      end += 1
    if end - start > 1:
      reserve(str_list, start, end-1)
      i = end
    else:
      i = end
  else:
    i += 1

print(str_list)
str_list.reverse()
print(&#39;&#39;.join(str_list))

# 采用正则表达式操作
str_re = re.split(r&#39;(\s+)&#39;,str)

str_re.reverse()
str_re = &#39;&#39;.join(str_re)
print(str_re)

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