PHP日期比较不起作用

Question

I'm trying to understand why this code works:

<?php
// $today = date("d/m/Y");
$today = date("Y-m-d");
$today_dt = new DateTime($today);

foreach ($records as $record) {
}
?>

<tr>
    <?php $dueDate = date("Y-m-d", strtotime($record->getField('Due Date'))); ?>
    <td><?php echo 'today is: ' . $today; ?></td>
    <td><?php echo 'expiry date is: ' . $dueDate; ?></td>
    <td> <?php $expire_dt = new DateTime($dueDate); ?> </td>
    <td><?php echo $expire_dt < $today_dt ? 'expire time less than today time':'expire time greater than today time';?></td>

but when I change the format of the date from Ymd to d/m/Y this fails with an error:

<?php
// $today = date("d/m/Y");
$today = date("d/m/Y");
$today_dt = new DateTime($today);

foreach ($records as $record) {

}
?>

    <tr>
<?php $dueDate = date("d/m/Y", strtotime($record->getField('Due Date'))); ?>
    <td><?php echo 'today is: ' . $today; ?></td>
    <td><?php echo 'expiry date is: ' . $dueDate; ?></td>
    <td><?php $expire_dt = new DateTime($dueDate); ?></td>
    <td><?php echo $expire_dt < $today_dt ? 'expire time less than today time' : 'expire time greater than today time';?></td>

The error is

'PHP Fatal error: Uncaught exception 'Exception' with message 'DateTime::__construct(): Failed to parse time string (19/06/2015) at position 0 (1)'

The line it references is:

$today_dt = new DateTime($today);

Answer 1

Using the DateTime class you don't have to format the input date the way you want it to display, you can display it in any format using format.

// Get todays date
$today_dt = new DateTime();

// Display date in specified format
echo $today_dt->format('d/m/Y');

Check out the PHP man page for more.

Answer 2

您使用的日期格式应为“ mm / dd / yyyy”，而不是“ dd / mm / yyyy”。