如何使用php计算图书馆罚款截止日期前的日期

Question

This is my code of library fines calculation

$currentdate= date('Y/m/d');

$start = new DateTime($returndate=$row['due_date']); <-- from database
$end = new DateTime($currentdate);
$days= $start->diff($end, true)->days;
$fines = $days > 0 ? intval(floor($days)) * ₱10 : 0;

I want to calculate borrowing books every day after due date cost ₱10 but it just counted the day and display like this sorry I'm beginner in php coding thank you

Answer 1

$end is currentday and because of that it will calculate a fine even if currentdate is less than duedate.
What you need is a if currentday is more than duedate, then calculate the fine.

$currentdate = date('Y/m/d');
$start = new DateTime($returndate=$row['due_date']); <-- from database
$end = new DateTime($currentdate);

if(strtotime($currentdate) > strtotime($returndate)){
    $days= $start->diff($end, true)->days;
    $fines = $days > 0 ? intval(floor($days)) * 10 : 0;
}

strtotime() will convert a date in string format to UNIX time (integer).

You can test the code here: https://3v4l.org/fl3IM

Edit:

Method 1.

$currentdate = date('Y/m/d');
$start = new DateTime($returndate=$row['due_date']); <-- from database
$end = new DateTime($currentdate);

$fines = 0;
if(strtotime($currentdate) > strtotime($returndate)){
    $days= $start->diff($end, true)->days;
    $fines = $days > 0 ? intval(floor($days)) * 10 : 0;
}

Now it will show a fine of 0 until someone has passed due date. (may look cluttered in the page)

---

Method 2.

$currentdate = date('Y/m/d');
$start = new DateTime($returndate=$row['due_date']); <-- from database
$end = new DateTime($currentdate);

if(strtotime($currentdate) > strtotime($returndate)){
    $days= $start->diff($end, true)->days;
    $fines = $days > 0 ? intval(floor($days)) * 10 : 0;
}

//some other code I guess...  

if(isset($fines)) echo $fines;

Here $fines is not set and will not be echoed unless someone is passed due date. This method probably will look the best on the page.
But I don't know exactly how your page is set up.