use strict;
use warnings;

my @strings = (
   q {Only literal \t's, \n's etc. here},
   qq{There's a real\nnewline in this},
   qq{A real\ttab\tdelimited\tstring},
   );

my $rxWS = qr{[\r\n\t\f]};

foreach my $string ( @strings )
{
    print qq{$string\n};
    print
       $string =~ $rxWS
       ? qq{Match found\n\n}
       : qq{No match\n\n}
}

##</code><code>##

Only literal \t's, \n's etc. here
No match

There's a real
newline in this
Match found

A real  tab     delimited       string
Match found