On Monday, July 7, 2014 10:46:19 AM UTC-4, Steven D'Aprano wrote: > On Mon, 07 Jul 2014 07:08:53 -0700, rxjwg98 wrote: > > > > > More specific, what does 're.M' means? > > > > > > Feel free to look at it interactively. re.M is a flag to control the > > meaning of the regular expression. It is short for re.MULTILINE, just as > > re.I is short for re.IGNORECASE: > > > > py> import re > > py> re.M == re.MULTILINE > > True > > py> re.I == re.IGNORECASE > > True > > > > > > They are just numeric flags: > > > > py> re.I > > 2 > > py> re.M > > 8 > > > > so you can combine then: > > > > > > py> re.I | re.M > > 10 > > > > > > re.M turns on "multi-line matching". This changes the meaning of the > > special characters ^ and $. > > > > Standard mode: > > ^ matches the start of the string > > $ matches the end of the string > > > > Multi-line mode: > > ^ matches the start of each line > > $ matches the end of each line > > > > > > Here is an example. Copy and paste this into the interpreter: > > > > > > import re > > text = """First line. > > Second line. > > Third line.""" > > pattern = "^.*$" # Match anything from the start to end. > > > > > > By default, . does not match newlines, so by default the regex matches > > nothing: > > > > > > py> re.search(pattern, text) is None # Nothing matches! > > True > > > > > > If you use MULTILINE mode, $ matches the end of the first line: > > > > > > py> re.search(pattern, text, re.M).group() > > 'First line.' > > > > > > If you add MULTILINE mode and DOTALL mode, it matches everything: > > > > py> re.search(pattern, text, re.M|re.S).group() > > 'First line.\nSecond line.\nThird line.' > > > > > > See the reference manual for more details: > > > > https://docs.python.org/3/library/re.html#module-contents > > (Python 3) > > > > https://docs.python.org/2/library/re.html#module-contents > > (Python 2) > > > > > > > > -- > > Steven
Your patter is: pattern = "^.*$" while my example has pattern: '(.*) are (.*?) .*' which does not have either '^' or '$' Why re.M has effects on my example? Thanks, -- https://mail.python.org/mailman/listinfo/python-list
