Unable to compare two dates

Question

I have an array and using foreach loop I am trying to check if the dinner_date matches the previous index dinner_date and if they don't i am assigning yes to variable called $newDate This is what the output looks line

array:4 [▼
  0 => array:3 [▼
    "request_id" => "48"
    "dinner_date" => "2016-05-16T10:00:00"
    "new_date" => "no"
  ]
  1 => array:3 [▼
    "request_id" => "51"
    "dinner_date" => "2016-05-16T10:00:00"
    "new_date" => "no"
  ]
  2 => array:3 [▼
    "request_id" => "50"
    "dinner_date" => "2016-05-27T10:00:00"
    "new_date" => "no"
  ]
  3 => array:3 [▼
    "request_id" => "52"
    "dinner_date" => "2016-05-27T10:00:00"
    "new_date" => "no"
  ]
]

This is my foreach loop

$dinnerDetails = array();
$lastDinnerDate = '';
$newDate = '';
foreach ($invitations as $invitation) {
    $lastDinnerDate = $invitation['dinner_date'];
    if ($invitation['dinner_date'] > $lastDinnerDate) {
        $newDate = 'yes';

    } else {
        $newDate = 'no';
    }

    $dinnerDetails[] = array(
        'request_id' => $invitation['request_id'],
        'dinner_date' => $invitation['dinner_date'],
        'new_dinner' => $newDate
    );
}

So as you can see in index 2 of array output it says new_date => no it should actually be yes because dinner_date of this index is different than the dinner_date of the index above.

So am I doing wrong here?

Answer 1

Change it to this :

$lastDinnerDate = '';
foreach ($invitations as $invitation) {
    $lastDinnerDate = $invitation['dinner_date'];
    $newDate = 'no';
    if ($lastDinnerDate != "") {
        if ($invitation['dinner_date'] > $lastDinnerDate) {
            $newDate = 'yes';
        } else {
            $newDate = 'no';
        }
    }
    $lastDinnerDate = $invitation['dinner_date'];
    $dinnerDetails[] = array(
        'request_id' => $invitation['request_id'],
        'dinner_date' => $invitation['dinner_date'],
        'new_dinner' => $newDate
    );
}

Answer 2

Comment: In your case they both are same, you need to store $lastDinnerDate = $invitation['dinner_date']; after the condition.

Add one more condition $lastDinnerDate != "" to your if condition and assign the `` after the in condition.

For the comparison you need to convert the datetime into timestamp.

foreach ($invitations as $invitation) {

    if (strtotime($invitation['dinner_date']) > $lastDinnerDate && $lastDinnerDate != "") {
        $newDate = 'yes';

    } else {
        $newDate = 'no';
    }
    $lastDinnerDate = strtotime($invitation['dinner_date']);

    $dinnerDetails[] = array(
        'request_id' => $invitation['request_id'],
        'dinner_date' => $invitation['dinner_date'],
        'new_dinner' => $newDate
    );
}

Answer 3

The main problem here is that you're storing the same values in every cycle, so the two dates will be the same every time, thus the execution will never reach the "yes" branch.

Also, you're trying to apply an arithmetic comparison operator for two strings, which will provide fake results:

$invitation['dinner_date'] > $lastDinnerDate

All you need to do is to use strtotime() . It basically parses any date format into a timestamp, which you can compare regularly:

strtotime($invitation['dinner_date']) > strtotime($lastDinnerDate)

It can parse a wide variety of date strings, for more info, visit the datetime.formats in the official manual.