Regular Expression for Finding and Deleting comments

[Jeremy]

On Tuesday, January 4, 2011 11:26:48 AM UTC-7, MRAB wrote:
> On 04/01/2011 17:11, Jeremy wrote:
> > I am trying to write a regular expression that finds and deletes (replaces with nothing) comments in a string/file.  Comments are defined by the first non-whitespace character is a 'c' or a dollar sign somewhere in the line.  I want to replace these comments with nothing which isn't too hard.  The trouble is, the comments are replaced with a new-line; or the new-line isn't captured in the regular expression.
> >
> > Below, I have copied a minimal example.  Can someone help?
> >
> > Thanks,
> > Jeremy
> >
> >
> > import re
> >
> > text = """ c
> > C - Second full line comment (first comment had no text)
> > c   Third full line comment
> >    F44:N 2    $ Inline comments start with dollar sign and go to end of line"""
> >
> > commentPattern = re.compile("""
> >      (^\s*?c\s*?.*?|             # Comment start with c or C
> >      \$.*?)$\n                           # Comment starting with $
> >      """, re.VERBOSE|re.MULTILINE|re.IGNORECASE)
> >
> Part of the problem is that you're not using raw string literals or
> doubling the backslashes.
> 
> Try soemthing like this:
> 
> commentPattern = re.compile(r"""
>      (^[ \t]*c.*\n|              # Comment start with c or C
>      [ \t]*\$.*)                 # Comment starting with $
>      """, re.VERBOSE|re.MULTILINE|re.IGNORECASE)

Using a raw string literal fixed the problem for me.  Thanks for the suggestion.  Why is that so important?

Jeremy