help needed to solve in regex

jesuashok has asked for the wisdom of the Perl Monks concerning the following question:

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Re: help needed to solve in regex by ikegami (Patriarch) on Jan 10, 2007 at 05:05 UTC
You're using a string where a regular expression is expected. `my $find_re = qr/1\.2\.3/i; ... grep /$find_re/, ... ...` [download] or `my $find_str = '1.2.3'; my $find_re = quotemeta($find_str); ... grep /$find_re/i, ... ...` [download] or `my $find_str = '1.2.3'; ... grep /\Q$find_str\E/i, ... ...` [download]	[reply] [d/l] [select]
Re^2: help needed to solve in regex by diotalevi (Canon) on Jan 10, 2007 at 05:59 UTC
You forgot the surround the pattern with \b markers. `/\b\Q$find\E\b/` ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply] [d/l]
Re^3: help needed to solve in regex by ikegami (Patriarch) on Jan 10, 2007 at 06:26 UTC
oh, I didn't notice that matched the third line. Unforunately, I don't agree with your solution. That is to say I don't think we can provide a solution with the information he provided us. For example, all of the following match his criteria, yet all are different: `/\b\Q$find\E\b/` `/(?<!\S)\Q$find\E/(?!\S)` `/\Q$find\E/(?!\.)` `/\Q$find\E$/` `/\Q$find\E$/m` `/\Q$find\E\z/` ... The op should have a look at perlre. (Or should I say "another look" since he should already have looked there when he started having problems with his regexp...)	[reply] [d/l] [select]
Re: help needed to solve in regex by chromatic (Archbishop) on Jan 10, 2007 at 06:30 UTC
Why grep with a one-element list rather than a standard pattern match?	[reply]
Re: help needed to solve in regex by Praveen (Friar) on Jan 10, 2007 at 05:40 UTC
Hi Try this `if ( grep ( /\Q$find\E$/i , $input_line ) ) {` [download]	[reply] [d/l]
Re: help needed to solve in regex by wazoox (Prior) on Jan 10, 2007 at 12:03 UTC
The problem is that "." matches any character in regexes, so `/1.2.3/` [download] Actually means match "1" followed by any character then "2" then any character then "3" . What others suggested is to escape the dots so that they only match dots, using the different ways available (because of course TIMTOWTDI). By the way if you need to try out your regexes in an easy and graphical way, I advise you to try the wonderful script regexperiment from paul Gaborit, I use it a lot and it saved me much time and effort.	[reply] [d/l]
Re: help needed to solve in regex by murugu (Curate) on Jan 10, 2007 at 11:30 UTC
Hi jesuashok, You can use `quotemeta` and `\b` Regards, Murugesan Kandasamy use perl for(;;);	[reply] [d/l] [select]