Newbie Regex Problem

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

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Re: Newbie Regex Problem by Joost (Canon) on Oct 19, 2007 at 21:20 UTC
As others have noted, `` is greedy, matching everything it can, which in your case of `.` means as many characters as possible (except newlines, see perlretut for the details). You can either make your . match non-greedily, using .? which makes it match the shortest substring that makes the overall match work, or you can explicitly exclude the , character from the part you want to match: `if ($test =~ m#LDAP://CN=([^,])#) { }` [download] Note that I used m# ... # syntax instead of "" quotes, since using a plain string as a regex literal can cause additional headaches, and using the usual // delimiters requires you to escape the / characters in your match. See the link for more information on perl's special quoting operators. updated: forgot to add the * to `[^,]` "What should it profit a man, if he should win a flame war, yet lose his cool?"*	[reply] [d/l] [select]
Re: Newbie Regex Problem by almut (Canon) on Oct 19, 2007 at 21:11 UTC
You need a non-greedy match: `if ($test =~ "LDAP://CN=(.*?),") {` [download] (note the question mark)	[reply] [d/l]
Re: Newbie Regex Problem by andyford (Curate) on Oct 19, 2007 at 21:12 UTC
The '' is greedy, matching as much as it can. To make it non-greedy, put a question mark after it. `if ($test =~ "LDAP://CN=(.?),.*") {` [download] non-Perl: Andy Ford	[reply] [d/l]
Re: Newbie Regex Problem by dsheroh (Monsignor) on Oct 19, 2007 at 21:24 UTC
Alternately, aside from going non-greedy, you could specify more exactly just what it is you're looking for. Namely, that you only want non-comma characters: `if ($test =~ "LDAP://CN=([^,]*),") {`	[reply] [d/l]
Re: Newbie Regex Problem by FunkyMonk (Chancellor) on Oct 19, 2007 at 21:12 UTC
`` is greedy, which means it will match the longest substring it can. You can force `` to be non-greedy by following it with `?` `if ($test =~ m{LDAP://CN=(.?),}) {` [download] You'll also note I've taken out the last `.`, as it serves no purpose and changed your string to a regexp. See perlre and perlretut for more information.	[reply] [d/l] [select]
Re: Newbie Regex Problem by omouse (Initiate) on Oct 20, 2007 at 15:28 UTC
If $test isn't part of a larger string, you can just slice it instead of using a regular expression. `$test="LDAP://CN=MyPc,OU=MyOu,DC=NyDomain,DC=com"; $CN = substr($test, 10, index($test, ",") - 10); print "$CN\n";` [download] You can slice off the "LDAP://CN=" since you know it'll always be there, then you slice to the first comma.	[reply] [d/l]


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