Re^2: Regex to ignore comment

Thanks for the comments AppleFritter

I don't want to do the regex $line =~ s/\s*#.*$//; becuse it might be in the pattern. such as

pattern = the number is #8  # number
[download]

where #8 is in the pattern

and # number is a comment

I was hoping that i could do a look behind and catch it that way.

But corion's way of doing this is really the same thing.

$line =~ s!#.*$!!; # strip off comments
my( $key, $value ) = split /=/, $line;
[download]

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Re^3: Regex to ignore comment by AppleFritter (Vicar) on Oct 20, 2015 at 20:19 UTC
I see. But doesn't that make the format itself ambiguous? Put another way, how can you tell the following two apart, programmatically? pattern = the number is #8 # number pattern = 255.257.0.0 # invalid, and BTW, this comment contains a # character To a human (or pony) reading this, it's obvious that the comment starts on the second `#` in the first line, and on the first `#` in the second line. But how would a program tell the difference? This is what I meant by quoting, BTW. If your format required you to write e.g. pattern = "the number is #8" # number to avoid this ambiguity, you'd have to deal with quoting, but at least you'd be able to rely on the first unquoted `#` character on a line to actually indicate a comment.	[reply]
Re^3: Regex to ignore comment by Laurent_R (Canon) on Oct 20, 2015 at 20:17 UTC
Well if `#` can be both part of your pattern and an indication that it is a comment to be removed, then you need to specify how to distinguish between the two cases. With an input string such as: `pattern = the number is #8 # number` [download] this would remove everything after (and including) the last `#` of your string: `s/#[^#]+$//;` [download] but this assumes that you always have a trailing comment in your input. But we have not way to know whether it will work with your other input lines (i.e. if there is always a trailing comment in your lines).	[reply] [d/l] [select]
Re^3: Regex to ignore comment by Corion (Patriarch) on Oct 20, 2015 at 20:18 UTC
How do you know the difference between: `pattern = the number is #8 # number` [download] and `pattern = the number is 9 #8 , changed 2015-10-20` [download] Maybe a comment really starts with `"# "` (hash and then a blank)?	[reply] [d/l] [select]