$string = '|123456|john+';
/\Q$string\E/        # Strings are still interpolated,
                     # but their contents are escaped.

##</code><code>##

$string = '|123456|john+';
/\Q$string/          # The \E is optional

##</code><code>##

/\Q|123456|john+\E/  # As long as the text doesn't
                     # contain "$", "@", the regexp
                     # delimiter (which is "/" here)
                     # or \E.

##</code><code>##

$string = quotemeta('|123456|john+');
/$string/