The escape sequence \Q ...\E  quotes, or protects most non-alphabetic characters. For instance,

   1. $x = "\QThat !^*&%~& cat!";
   2. $x =~ /\Q!^*&%~&\E/; # check for rough language

It does not protect $ or @ , so that variables can still be substituted.
##</code><code>##

use warnings;
use strict;

print "Yes!\n" if ( '$@' =~ m|\$\@| ); 
# prints "Yes!"

##</code><code>##

use warnings;
use strict;

my $string = '@@@';
if ( $string =~ m|\$\@| ){
	print "Yes!\n";
}
else {
	print "\'$string\' did not match...\n";
}
# prints "'@@@' did not match..."