Using string literal in regexp

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

I have a scalar string..

   my $foo = '$@!#@#$^$#@^';
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..and I want to incorporate it into a regular expression such that the characters of the string will be matched literally, no matter what characters they are.

    my $bigfoo='aabbaaa$@!#@#$^$#@^bbabaaba';
    assert $bigfoo =~ /(a|b)*$foo(a|b)*/;
[download]

What is the correct way to interpolate a string literal into a regular expression?

Thanks,

-Andrew.

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Re: Using string literal in regexp by davorg (Chancellor) on Jun 16, 2006 at 15:55 UTC
quotemeta or `\Q ... \E`. `my $bigfoo=quotemeta('aabbaaa$@!#@#$^$#@^bbabaaba'); assert $bigfoo =~ /(a\|b)$foo(a\|b)/;` [download] or `my $bigfoo='aabbaaa$@!#@#$^$#@^bbabaaba'; assert $bigfoo =~ /(a\|b)\Q$foo\E(a\|b)/;` [download] -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l] [select]
Re: Using string literal in regexp by sh1tn (Priest) on Jun 16, 2006 at 17:43 UTC
You should use `qr` operator. If the character is special one, escape it with '\'. You may want to read this manual - perlre	[reply] [d/l]
Re^2: Using string literal in regexp by chromatic (Archbishop) on Jun 17, 2006 at 07:32 UTC
I don't think this is helpful. How does `qr//` help? Interpolation happens there too! How do you perform generalized backslash escaping on an arbitrary string? Do you run it through another regex first? Do you recreate the behavior of quotemeta or `\Q...\E` then, perhaps badly? davorg has given far better advice.	[reply] [d/l] [select]