How do you comment a Perl regular expression?

Question

How do you put comments inside a Perl regular expression?

Answer 1

Use the /x modifier:

my $foo = "zombies are the bombies";
if ($foo =~ /
             zombie  # sorry pirates
            /x ) {
    print "urg. brains.\n";
}

Also see the first question in the perl6faq.

Also it wouldn't hurt to read all of perlre while you're at it.

Answer 2

Even without the /x modifier, you can enclose comments in (?# ... ):

my $foo = "zombies are the bombies";
if ( $foo =~ /zombie(?# sorry pirates)/ ) {
    print "urg. brains.\n";
}