Regex help

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

Hi Monks,

I have a bit more of a complicated regex which I am stuck with. User types in the string to be matched, e.g. toilet(32), and this should then be whacked into a regex to match to a variable.

I know the brackets are causing a problem, so the input string should go from /toilet(32)/ to this /toilet$32$/so the regex can function properly. Can anyone help me witha substitution regex to scan this string and prepend all non-complying characaters with "\".

Also, some of the strings will actually be some code, with the regex inside.e.g.

$line = 'if($appliance =~ /toilet(32)/)';
[download]

Should be:

$line = 'if($appliance =~ /toilet\(32\)/)';
[download]

If that makes sense :-) Cheers

Comment on Regex help Select or Download Code

Replies are listed 'Best First'.
Re: Regex help by Anonymous Monk on May 06, 2009 at 11:12 UTC
quotemeta	[reply]
Re^2: Regex help by moritz (Cardinal) on May 06, 2009 at 11:23 UTC
... or `/\Q$variable\E/` (which uses quotemeta under the hood)	[reply] [d/l]
Re^3: Regex help by ccn (Vicar) on May 06, 2009 at 11:31 UTC
What is the reason to put `\E` at the end of a regexp?	[reply] [d/l]
Re^4: Regex help by moritz (Cardinal) on May 06, 2009 at 11:53 UTC
Re^4: Regex help by ikegami (Patriarch) on May 06, 2009 at 15:21 UTC
Re^2: Regex help by bingohighway (Acolyte) on May 06, 2009 at 12:19 UTC
Is there a way of running quotemeta between bounds however, e.g. `$line = 'if($appliance =~ /toilet(32)/)';` [download] Should be: `$line = 'if($appliance =~ /toilet$32$/)';` [download] In a simple one-liner? Cheers!	[reply] [d/l] [select]
Re^2: Regex help by bingohighway (Acolyte) on May 06, 2009 at 11:51 UTC
Superb :-) It's amazing the little jewels Perl has hidden away.	[reply]
Re: Regex help by planetscape (Chancellor) on May 07, 2009 at 03:32 UTC
You may also wish to have a look at quotes in Perl. HTH, planetscape	[reply]
Re: Regex help by JavaFan (Canon) on May 06, 2009 at 11:36 UTC
Why use a regexp in that case? `index` will do as well.	[reply] [d/l]
Re: Regex help by vinoth.ree (Monsignor) on May 06, 2009 at 13:19 UTC
quotemeta is the best way to do this If u want to this by the explicitly instead of using the quatemeta just add the character you want to prefix with the "\" in the substitute. `while(<>){ $_=~ s/([\$\|\\|\|\[\|\)\|\\\|\/\|\(])/\\$1/g; print; }` [download] Vinoth,G	[reply] [d/l]
Re^2: Regex help by bingohighway (Acolyte) on May 06, 2009 at 13:34 UTC
How about reading a string, searching for the regex (i.e. encased by `/$regex/`) and only doing this substitution within the regex delimeters? Cheers!	[reply] [d/l]
Re: Regex help by bichonfrise74 (Vicar) on May 06, 2009 at 22:57 UTC
I really like quotemeta.	[reply]