Question

Although this question is similar to this thread

I think I might be doing something wrong at the time of constructing the code with the Regular Expression.

I want to match anything in a line up to a comment (“#”) or the end of the line (if it doesn’t have a comment).

The regex I am using is: (.*)(#|$)

(.*) = Everything
(#|$) = comment or end of line

The code:

OPTION = re.compile(r'(?P<value>.*)(#|$)')
file = open('file.txt')
lines = file.read()
for line in lines.split('\n'):
    get_match = OPTION.match(line)
    if get_match:
        line_value = get_match.group('value')
        print "Match=  %s" % line_value

The above works but does not strip out the comment.
If the file has a line like:

this is a line   # and this is a comment

I still get the whole line when running the code.

Am I missing additional values/information in the regular expression or do I need to have a change on the code?

Answer 1

The * is greedy (consumes as much of the string as it can) and is thus consuming the entire line (past the # and to the end-of-line). Change “.*” to “.*?” and it will work.

See the Regular Expression HOWTO for more information.