Question

I need array keys in json array to be integers. Now they are strings. Could you tell me where is my mistake?

   $i = 0;
   while($i < 7) {
       isset($ips[date('d', $week_start + $i * 86400)])
           ? $ips[(int)date('d', $week_start + $i * 86400)] = count(date('d', $week_start + $i * 86400))
           : $ips[(int)date('d', $week_start + $i * 86400)] = 0;

       isset($time[date('d', $week_start + $i * 86400)])
           ? $time[(int)date('d', $week_start + $i * 86400)] = count(date('d', $week_start + $i * 86400))
           : $time[(int)date('d', $week_start + $i * 86400)] = 0;

       $i++;
   }

   return json_encode(array('unique' => $time, 'impressions' => $ips));

Answer 1

What you want is not possible with json_encode or json format

Look at this 2 arrays

$array = array("A","B","C","D");
$array2 = array(2=>"A",7=>"B",11=>"C",70=>"D");

Run

 var_dump($array,$array2);

Output

array
  0 => string 'A' (length=1)
  1 => string 'B' (length=1)
  2 => string 'C' (length=1)
  3 => string 'D' (length=1)
array
  2 => string 'A' (length=1)
  7 => string 'B' (length=1)
  11 => string 'C' (length=1)
  70 => string 'D' (length=1)

You can see in PHP the are both Array

Now run

 var_dump(json_encode($array),json_encode($array2));

Output

string '["A","B","C","D"]' (length=17)
string '{"2":"A","7":"B","11":"C","70":"D"}' (length=35)

Conclusion

If you are setting array keys and those keys does not start with 0 and increase serially it would be encoded as json object

If you want just arrays

 var_dump(json_encode(array_values($array2)));

Output

 string '["A","B","C","D"]' (length=17)