Call to undefined method DateTime::add() - PHP Version 5.4.6

Question

I've got the following function which I had help building at this topic

function nextDelivery($day,$o_date,$oc) {
    $day_names = array('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday');
    $day_num = array_search($day, $day_names);
    $o_date = new DateTime($o_date);
    $o_day_num = $o_date->format('w');
    $day_diff = ($day_num - $o_day_num) % 7;
    if($day_diff<0){$day_diff=7+$day_diff;}elseif($day_diff==0){$day_diff=7;}
    if($oc==2){$day_diff+7;}
    $order_day = clone $o_date;
    $order_day->add(new DateInterval("P".$day_diff."D"));
    return $order_day->format('Y-m-d H:i:s');
}

Now I've just changed my time stamp to Pacific/Auckland, as my host was America/Denver. This has changed everything except for files run using Cron Jobs, they are still outputting the old timestamp. Now if I run this function on a page in my site it woks fine, but if a cron job file, using the exact same function runs I get the following error

PHP Fatal error: Call to undefined method DateTime::add() in ***** on line 156

which is $order_day->add(new DateInterval("P".$day_diff."D"));

This is my info http://www.dpdesignz.co.nz/homefresh/lib/php_info.php

Does anyone have any ideas as to why this may be happening?

Answer 1

DateTime::add was added in PHP 5.3.0. Your cron job is probably using an older version. Try to upgrade, or change the version it uses. If you can't do that, then, as mentioned in the notes: DateTime::modify is an alternative.

Answer 2

PHP uses a different php.ini file depending on whether it's running from the CLI or as a CGI from the webserver. It sounds like the CLI php.ini may be pointing to something incorrect.