Regex with variables?

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

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Re: Regex with variables? by gjb (Vicar) on Aug 22, 2003 at 14:55 UTC
Your solution will work if you replace the `=` by `=~`. Hope this helps, -gjb-	[reply] [d/l] [select]
Re: Re: Regex with variables? by Quadzilla (Initiate) on Aug 22, 2003 at 15:05 UTC
Thanks gjb, I feel like an idiot... I've come unbound!	[reply]
Re: Regex with variables? by tcf22 (Priest) on Aug 22, 2003 at 14:59 UTC
Use `qr//`. It is used to store a regex in a variable. Think you want something like this. `my $re = qr/.+\-(.+)/; $foo =~ s/$re/$1/;` [download] but if all are in domain-computer form, you could just use `$foo =~ s/.+\-(.+)/$1/;` [download] Update: but on second thought the first way could run in a loop and you could just define the regex before the loop using `qr//`. That would probably be more efficient. Example: `use strict; my $re = qr/.+\-(.+)/; while(<DATA>){ s/$re/$1/; print; } __DATA__ domain-comp1 domain-comp2 domain-comp3` [download] Output: `comp1 comp2 comp3` [download]	[reply] [d/l] [select]
Re: Re: Regex with variables? by Quadzilla (Initiate) on Aug 22, 2003 at 15:13 UTC
Thanks tcf22! Thanks for taking the time to answer my question! That's exactly what I was trying to achieve. “Pie Iesu Domine. Dona eis Requiem.” Whack!	[reply]
Re: Regex with variables? by tachyon (Chancellor) on Aug 22, 2003 at 15:46 UTC
The only issue with using a var as the pattern (other than your missing =~ or course) is that it MAY contain regex metachars. quotemeta and its RE friends \Q and \E are your friends. Do: `$foo =~ s/\Q$find\$E/$replace/g;` [download] cheers tachyon s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print	[reply] [d/l]
Re: Regex with variables? by CombatSquirrel (Hermit) on Aug 22, 2003 at 15:53 UTC
Adiing to what the others said, if `$scalar` does not contain a RegEx, but a string that you want to match, you might be interested in the `quotemeta(...)` function, which avoids, for example, `$scalar = '.';` to match the whole string and transforms it to `\.\`. Just do something like `# first possibility $scalar = quotemeta('.*'); $foo =~ s/$scalar/string/; # second possibility chomp($scalar = <>); $scalar = quotemeta($scalar); $foo =~ s/$scalar/string/;` [download] Please note also that a subtitution substitues a pattern by a string, and not by a pattern. (This is probably what you meant, but some people try things like `s!<a>\d{3}</a>!\d{3}!` and wonder why it doesn't work) Cheers, CombatSquirrel.	[reply] [d/l] [select]
Re: Regex with variables? by Not_a_Number (Prior) on Aug 22, 2003 at 18:51 UTC
...and here's a non-regex solution: `while ( <DATA> ) { my $comp = (split /-/)[-1]; print $comp; } __DATA__ domainA-comp1 domainB-comp2 domainC-comp3` [download] dave	[reply] [d/l]


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