python如何使用正则表达式的前向、后向搜索及前向搜索否定模式详解

#python 3.6 
#蔡军生 
#http://blog.csdn.net/caimouse/article/details/51749579 
# 
import re 
 
address = re.compile( 
 ''''' 
 # A name is made up of letters, and may include "." 
 # for title abbreviations and middle initials. 
 ((?P<name> 
  ([\w.,]+\s+)*[\w.,]+ 
  ) 
  \s+ 
 ) # name is no longer optional 
 
 # LOOKAHEAD 
 # Email addresses are wrapped in angle brackets, but only 
 # if both are present or neither is. 
 (?= (<.*>$)  # remainder wrapped in angle brackets 
  | 
  ([^<].*[^>]$) # remainder *not* wrapped in angle brackets 
  ) 
 
 <? # optional opening angle bracket 
 
 # The address itself: username@domain.tld 
 (?P<email> 
  [\w\d.+-]+  # username 
  @ 
  ([\w\d.]+\.)+ # domain name prefix 
  (com|org|edu) # limit the allowed top-level domains 
 ) 
 
 >? # optional closing angle bracket 
 ''', 
 re.VERBOSE) 
 
candidates = [ 
 u'First Last <first.last@example.com>', 
 u'No Brackets first.last@example.com', 
 u'Open Bracket <first.last@example.com', 
 u'Close Bracket first.last@example.com>', 
] 
 
for candidate in candidates: 
 print('Candidate:', candidate) 
 match = address.search(candidate) 
 if match: 
  print(' Name :', match.groupdict()['name']) 
  print(' Email:', match.groupdict()['email']) 
 else: 
  print(' No match') 

Candidate: First Last <first.last@example.com>
 Name : First Last
 Email: first.last@example.com
Candidate: No Brackets first.last@example.com
 Name : No Brackets
 Email: first.last@example.com
Candidate: Open Bracket <first.last@example.com
 No match
Candidate: Close Bracket first.last@example.com>
 No match

#python 3.6 
#蔡军生 
#http://blog.csdn.net/caimouse/article/details/51749579 
# 
import re 
 
address = re.compile( 
 ''''' 
 ^ 
 
 # An address: username@domain.tld 
 
 # Ignore noreply addresses 
 (?!noreply@.*$) 
 
 [\w\d.+-]+  # username 
 @ 
 ([\w\d.]+\.)+ # domain name prefix 
 (com|org|edu) # limit the allowed top-level domains 
 
 $ 
 ''', 
 re.VERBOSE) 
 
candidates = [ 
 u'first.last@example.com', 
 u'noreply@example.com', 
] 
 
for candidate in candidates: 
 print('Candidate:', candidate) 
 match = address.search(candidate) 
 if match: 
  print(' Match:', candidate[match.start():match.end()]) 
 else: 
  print(' No match') 

Candidate: first.last@example.com
 Match: first.last@example.com
Candidate: noreply@example.com
 No match