if ( $value and $value !~ /^(?:(\d+)d)?(?:\s*(\d+)h)?$/i )
   {
   $result  = "Please only enter time in one of these three formats: '3d', '4d 3h', '22h'";
   }
else
   {
   $day = $1 || 0;
   $hour = $2 || 0;
   }