What's the difference between re.DOTALL and re.MULTILINE? [duplicate]

What's the difference between re.DOTALL and re.MULTILINE? [duplicate]

They are quite different. Yes, both affect how newlines are treated, but they switch behaviour for different concepts.

• re.MULTILINE affects where ^ and $ anchors match.

  Without the switch, ^ and $ match only at the start and end, respectively, of the whole text. With the switch, they also match just before or after a newline:

  >>> import re
  >>> re.search('foo$', 'foo\nbar') is None  # no match
  True
  >>> re.search('foo$', 'foo\nbar', flags=re.MULTILINE)
  <_sre.SRE_Match object; span=(0, 3), match='foo'>
  

• re.DOTALL affects what the . pattern can match.

  Without the switch, . matches any character except a newline. With the switch, newlines are matched as well:

  >>> re.search('foo.', 'foo\nbar') is None  # no match
  True
  >>> re.search('foo.', 'foo\nbar', flags=re.DOTALL)
  <_sre.SRE_Match object; span=(0, 4), match='foo\n'>

 

作者:Chuck Lu    GitHub