针对DateTime对象的Foreach循环

Question

I'am writing a small program that basically adds a fee to book if it is overdue just like a library.

So my thoughts are for each day that the book is late then there will be a fee added

IE: if the book is overdue for 5 days then the fee would be £10 = £2 a day.

Here is my code so far, not sure if it would be a "foreach" to be honest but i guess so

<?php
class Book
{

public $timeOverdue;

public function isBookOverdue()
{
    $returnedDate = new \DateTime('05/19/2015');
    $dueDate = new DateTime('05/08/2015');

    var_dump('returndDate', $returnedDate);
    var_dump('dueDate', $dueDate);

    if ($returnedDate > $dueDate) {

        echo 'Book is overdue.' . PHP_EOL;
        // $isBookOverdueStatus = true;
        $timeOverdue = date_diff( $returnedDate, $dueDate);
        echo $timeOverdue->format("%m month, %d days (total: %a days)") . PHP_EOL;
        var_dump($timeOverdue);

    } else {
        echo "Book is not overdue" .PHP_EOL. "Book has been returned" . PHP_EOL;
        die();
    }
}
}

$returnOfABook = new Book();
$returnOfABook->isBookOverdue();
$returnOfABook->addOverdueFee();

Then here is kind of what im thinking is possible? more sudo code than anything:

// public function addOverdueFee($timeOverdue)
// {
//   foreach ($timeOverdue as "day" => 1) {
//       // add fee
//   }
// }

and just for reference here is the date object that i want the loop to be running on:

object(DateInterval)#4 (15) {
["y"]=>
int(0)
["m"]=>
int(0)
["d"]=>
int(11)
["h"]=>
int(0)
["i"]=>
int(0)
["s"]=>
int(0)
["weekday"]=>
int(0)
["weekday_behavior"]=>
int(0)
["first_last_day_of"]=>
int(0)
["invert"]=>
int(1)
["days"]=>
int(11)
["special_type"]=>
int(0)
["special_amount"]=>
int(0)
["have_weekday_relative"]=>
int(0)
["have_special_relative"]=>
int(0)
}

So i thinkkkk that it would be something along the lines of this?

foreach($array as $key => $value)
{
  //do stuff
}

Im still learning a lot so any tips, suggestions would be great, Thank you!

Answer 1

Just get the number of days the book is overdue and multiply it by 2. You already have everything you need as timeOverdue contains the number of days the book is overdue.

if ($returnedDate > $dueDate) {
    $timeOverdue = date_diff( $returnedDate, $dueDate);
    $amountToPay = $timeOverdue->days * 2;
}