foreach(@Array1)
{
        $string1 = $_;
        foreach(@Array2)
        {
                my string2 = $_;
                my $result = index($string2, $string1);
                if($result <= 0)
                {
                        print $string1, " is not found in ", $string2,"\n";
                }
        }
}

##</code><code>##

my $string = "FFF NNN JKK III LLL QQQ";
my $substr = "LLL";

my $result = index($string, $substr);
if($result > 0)
{
        print "Result: $result\n";
}
else
{
        print "not found";