构建一个Carbon对象数组 - PHP

Question

I'm confused trying to add an create an array of date instances with carbon. What I'm trying to achieve is an array with one carbon object for each day in between 2 dates.

Here's what I have so far:

// Get oldest and newest date by sorting the array by created_at
usort($data, function($a, $b) {
    return $a->created_at <=> $b->created_at;
});

$a = end($data);
$to  = $a->created_at; //-> Newest date
$from = $data[0]->created_at; //-> Oldest date

// Work out the difference between to and from dates
$carbonTO = new Carbon($to);
$carbonFrom = new Carbon($from);
$diff = $carbonFrom->diffInDays($carbonTO);

// Write the dates to an array
$i = 0;
while ($diff >= 0) {
    $filters[$i] = $carbonFrom->addDays($i);
    $diff--;
    $i++;
    var_dump($filters);
}

die();
return $filters;

So the var_dump from within the loop echo's this:

array(1) { 
    [0]=> object(Carbon\Carbon)#238 (3) { 
        ["date"]=> string(26) "2016-01-17 19:04:49.000000" 
        ["timezone_type"]=> int(3) 
        ["timezone"]=> string(3) "UTC" 
        } 
 } 

array(2) { 
    [0]=> object(Carbon\Carbon)#238 (3) { 
        ["date"]=> string(26) "2016-01-18 19:04:49.000000" 
        ["timezone_type"]=> int(3) 
        ["timezone"]=> string(3) "UTC" 
        } 
     [1]=> object(Carbon\Carbon)#238 (3) { 
         ["date"]=> string(26) "2016-01-18 19:04:49.000000" 
         ["timezone_type"]=> int(3) 
         ["timezone"]=> string(3) "UTC" 
         } 
      }

As you can see the second time I output the array the key of 0 has been overwritten by the newer date of 2016-01-18. Anyone have any ideas why?

I'm running php 7.0.0 on mamp with Larvel 5.2.

Answer 1

In PHP, except where otherwise noted, objects are assigned by reference rather than by value. That means that every time you assign an object to a variable you just store a reference to the same object. That's shown in your var_dump() code, all objects are the same #238:

object(Carbon\Carbon)#238

The general solution is to either use an immutable object (if available) or just clone the existing one:

while ($diff >= 0) {
    $filters[$i] = clone $carbonFrom->addDays($i);
    $diff--;
    $i++;
    var_dump($filters);
}