regex matching on metacharacters

slugger415 has asked for the wisdom of the Perl Monks concerning the following question:

Hi all, sorry if this is a naive question but I've searched around the web and haven't found a good answer, including https://perldoc.perl.org/perlre#Metacharacters.

How do I match a regex that contains metacharacters that are used in matching, such as asterisks, parens, etc.? Without escaping each?

I have two variables set, both containing asterisks, and a regex comparison:

#! /usr/bin/perl
my $v1 = "*hello";
my $v2 = "*hello";

if ($v1 =~ /$v2/){
 print "match\n";    
}
[download]

This obviously results in a Quantifier follows nothing in regex error. I can escape out the asterisk and it works fine:

$v2 =~ s/\*/\\\*/g;
[download]

But is there a more elegant way to do that, one that might also pick up some of the others?

thanks

Comment on regex matching on metacharacters Select or Download Code

Replies are listed 'Best First'.
Re: regex matching on metacharacters by LanX (Saint) on Jul 21, 2022 at 00:06 UTC
> But is there a more elegant way to do that, one that might also pick up some of the others? yes, see `quotemeta` resp. `\Q` and `\E` ° demo `>perl $v1 = "hello"; $v2 = "hello"; print quotemeta($v2),"\n"; print "match" if $v1 =~ /\Q$v2/; __END__ \*hello match >` [download] Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery} °) also `perlre#Quoting-metacharacters`	[reply] [d/l]
Re^2: regex matching on metacharacters by slugger415 (Monk) on Jul 21, 2022 at 03:32 UTC
thank you!	[reply]
Re: regex matching on metacharacters by hippo (Bishop) on Jul 21, 2022 at 09:15 UTC
Do you really want a regex match or are you actually trying to perform a substring match? If the latter, then consider index instead. `#!/usr/bin/env perl use strict; use warnings; my $str = 'You say hello, but you mean goodbye.'; my $substr = '*hello'; print "match\n" if index ($str, $substr) > -1;` [download] 🦛	[reply] [d/l]