Using regular expressions in python

while doing asian beauty pictures

I have learned more modes in the front, including forward search, backward search, positive mode, and negative mode. This time I will learn another one, which is the backward search positive mode, which means that the string that has been scanned, and I want to regret it to see if it can be matched. Its syntax is: (?<=pattern). For example, the following example is used to identify Twitter accounts, but this pattern will only match and will not appear in the matching string, as follows:
 

[python]  view plain copy  

 

 

1. #python 3.6  
2. #Cai Junsheng   
3. # http://www.meimei689.com 
4. #  
5. import re  
6.   
7. twitter = re.compile(  
8.     ''''' 
9.     # A twitter handle: @username 
10.     (?<=@) 
11.     ([\w\d_]+)       # username 
12.     ''',  
13.     re.VERBOSE)  
14.   
15. text = '''''This text includes two Twitter handles. 
16. One for @caimouse, and one for the author, @caijunsheng. 
17. '''  
18.   
19. print(text)  
20. for match in twitter.findall(text):  
21.     print('Handle:', match)  

 The resulting output is as follows:
 This text includes two Twitter handles.
One for @caimouse, and one for the author, @caijunsheng.