Matching parenthesis in a string

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

Hi
I have a script where I need to match strings with parenthesis to string items in an array. here is a part of it:

@array = ("text1_(Right):662:19990913:662:19990913:1",
"text2(Right):8000:20020116:8000:20020116:1",
"text3:6800:20021015:6900:20021014:1");

$Symbol= "text1_(Right)";

foreach $item (@array){
      if ($item =~ m/$Symbol/i) {
       print "$item\n";
         }
}
[download]

If I try to match "(Right)" to items in the array, I'll get 2 matches but the way it is combined with some other text, even if the exact match exists in the array, as in the example, I don't get any results. There probably is something I ought to do, but I don't know what I am missing here.

I appreciate any help.
Thanks,
Ciamack

Edit by tye to add CODE tags and remove most BR tags

Comment on Matching parenthesis in a string Download Code

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Re: Matching parenthesis in a string by zigdon (Deacon) on Oct 15, 2002 at 15:32 UTC
Since ()s are metachars for a regexp, you're actually matching "text1_Right" - which doesn't exist in your example. What you'll have to do is escape the ()s in your string: `@array = ("text1_(Right):662:19990913:662:19990913:1", "text2(Right):8000:20020116:8000:20020116:1", "text3:6800:20021015:6900:20021014:1"); $Symbol= "text1_(Right)"; foreach $item (@array){ if ($item =~ m/\Q$Symbol/i) { print "$item\n"; } }` [download] See perlop for the use of \Q -- Dan	[reply] [d/l]
Re: Matching parenthesis in a string by Abigail-II (Bishop) on Oct 15, 2002 at 15:33 UTC
If you want to do exact matching, probably the simplest is to use `index()`. Or to "quote meta" your search pattern, with either `quotemeta` or `\Q .. \E`. Abigail	[reply] [d/l] [select]
Re: Matching parenthesis in a string by John M. Dlugosz (Monsignor) on Oct 15, 2002 at 19:37 UTC
The easiest thing is to use \Q when interpolating the string into your regex operator. But why does that work? It changes ( to $, etc. You would write m/\(Right$/ normally. When interpolating, it's confusing because the backslashes are used by both the quote and the regex, and parens are not special to quotes. You would have to get a backslash into the regex, and that would require escaping that out in the quote! `$Symbol= "\$Right\$"`.	[reply] [d/l]