Re: Regex to ignore comment

So, if I understand correctly:

your file can contain comments on pattern lines (and others, too?);
comments are indicated by a # character, and span the entire rest of the line;
you want to process any line that has comments as if it did not.

Assuming you don't have to pay attention to quoting (i.e. pattern declarations that contain quoted #'s), I think the easiest way to accomplish that would be to simply remove any possible comments before parsing a line, i.e.:

while(my $line = <DATA>) {

    chomp $line ;
    $line =~ s/\s*#.*$//;

    # ...
}
[download]

Here's a few more tips while I'm at it, too.

This bit in the pattern regex:
```
[\w\d\s\\\/\.\-\@\!\$\%\^\&\*\:\;\,\<\>]
[download]
```
strikes me as an attempt to negate a character class without actually negating it. Are you trying to say "any character other than #" there? If so, you can use [^#] instead.
In the following regex:

/regex\s*=*\s*(.+)|regex\s*=*\s*/
[download]

What is the second part of the alternation for? Why not use (.*) in the first part instead? (The same thing applies to the pattern regex, really.)
Speaking of which, you use $1 even though it may not captured anything. Is that what you intended? (And you only use $pattern once; might as well get rid of it.)
Use a while loop instead of a foreach loop; may other monks correct me if I'm wrong, but my understanding is that using foreach will cause all data to be read into memory and then iterated over, which could be an issue depending on how much data you need to handle. while will read your data one line at a time.
I'd also suggest fixing the indenting; don't indent the foreach loop itself, and use consistent indenting inside it (e.g. don't indent the next if statements near the top an extra level).

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Re^2: Regex to ignore comment by crusty_collins (Friar) on Oct 20, 2015 at 19:32 UTC
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 /=/, $line;` [download]	[reply] [d/l] [select]
Re^3: Regex to ignore comment by AppleFritter (Vicar) on Oct 20, 2015 at 20:19 UTC
I see. But doesn't that make the format itself ambiguous? Put another way, how can you tell the following two apart, programmatically? pattern = the number is #8 # number pattern = 255.257.0.0 # invalid, and BTW, this comment contains a # character To a human (or pony) reading this, it's obvious that the comment starts on the second `#` in the first line, and on the first `#` in the second line. But how would a program tell the difference? This is what I meant by quoting, BTW. If your format required you to write e.g. pattern = "the number is #8" # number to avoid this ambiguity, you'd have to deal with quoting, but at least you'd be able to rely on the first unquoted `#` character on a line to actually indicate a comment.	[reply]
Re^3: Regex to ignore comment by Laurent_R (Canon) on Oct 20, 2015 at 20:17 UTC
Well if `#` can be both part of your pattern and an indication that it is a comment to be removed, then you need to specify how to distinguish between the two cases. With an input string such as: `pattern = the number is #8 # number` [download] this would remove everything after (and including) the last `#` of your string: `s/#[^#]+$//;` [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]