Save the results of the date difference on PHP - php

Question

how to save the results of the date difference to be saved to the database ?
public function save(){
$item = $this->input->post('item');
$date_in = $this->input->post('date_in'); //date in
$date_out = $this->input->post('date_out'); // date out
$hasil = $date_in->diff($date_out);
//echo $hasil->format('%a'); I will save these results to the database
$data_insert = array(
'item' => $item,
'date_in' => $date_in,
'date_out' => $date_out,
'selisih' => $hasil
);
//url save
}

Answer 1

String don't have method diff, diff is the method of DateTime, you need to change string to DateTime.
And it will return DateInterval object, you can get the total days by format('%a') and insert to database;
$hasil = (new DateTime($date_in))->diff(new DateTime($date_out));
$hasil = $hasil->format('%a');
$data_insert = array(
'item' => $item,
'date_in' => $date_in,
'date_out' => $date_out,
'selisih' => $hasil
);
$this->db->insert('mytable', $data_insert);

Answer 2

If you want to get difference you can get it with Carbon easily using diffInDays Example code for you :
$first = \Carbon\Carbon::createFromFormat('Y-m-d H:s:i', $date_in);
$second = \Carbon\Carbon::createFromFormat('Y-m-d H:s:i', $date_out);
$diff_in_days = $second->diffInDays($first);
Or get it without Carbon :
$first = new DateTime($date_in);
$second = new DateTime($date_out);
$interval = $first->diff($second);