Variable in regex...

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

Hola Monks, I am using the =~ to search for an instance of a certian string in an array, but every time one of the strings in the array contains special chars. I get an error:

Unmatched ( in regex; marked by <-- HERE in m/.*"blah blah ( <-- HERE 
+blah blah"
.*/ at blah.pl line 53.
[download]

Here's the code:

if ($lhs[0] =~ /.*$rhs.*/)
{  $matches++;  }
else {  print "Error: $lhs[0] = $rhs[1] \n"; diff++; }
[download]

2005-01-07 Janitored by Arunbear - added code tags, as per Monastery guidelines

Comment on Variable in regex... Select or Download Code

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Re: Variable in regex... by Roy Johnson (Monsignor) on Jan 07, 2005 at 21:05 UTC
Death to dot-star! The right tool for this job is `index`, not a regex. Also, use code tags in your post, so your brackets don't get specially interpreted. Caution: Contents may have been coded under pressure.	[reply] [d/l]
Re: Variable in regex... by amw1 (Friar) on Jan 07, 2005 at 20:57 UTC
try `if($lhs[0] =~ /.\Q$rhs[1]\E./) { $matches++; } else { print "Error: $lhs[0] = $rhs[1]\n"; $diff++; }` [download]	[reply] [d/l]
Re: Variable in regex... by trammell (Priest) on Jan 07, 2005 at 21:47 UTC
See also How do I escape metacharacters in a user-defined string?.	[reply]
Re: Variable in regex... by ambrus (Abbot) on Jan 07, 2005 at 21:42 UTC
A similar question has come up recently: Opening files, comparing strings. Should be simple!?	[reply]
Re: Variable in regex... by ww (Archbishop) on Jan 07, 2005 at 21:13 UTC
Also, when you get error messages (of the sort you posted) on a regex, give us enough literal output to UNambiguously id what the reference is, just before the second: `<--HERE` [download] The second "<--HERE" in your error line tells EXACTLY where the error exists. In some regexen, especially those with multiple similar elements, knowing that the error occured at a close_paren may not be enough. In this case (even before the janitorial services) spotting the error was not hard, but note also the suggestion for an alternate approach. *Updated to clarify (originally sloppy)* syntax in first paragraph.**	[reply] [d/l]
Re: Variable in regex... by perlsen (Chaplain) on Jan 08, 2005 at 09:48 UTC
you have to use the quotemeta for your search string to include the special charecter in your search `quotemeta($rhs); or \q$rhs[1]\E` [download] Regards, Senthil Kumar.k	[reply] [d/l]