OK here is my code, processing the JSON below it.

$json = file_get_contents('https://courier-api.danielpikilidis.com/track-one/elta/CP423172129GR');
$json_data = json_decode($json);

$last = $json_data;

echo $last->data->CP423172129GR->locations[0]->datetime."<br>";
echo $last->data->CP423172129GR->locations[0]->location."<br>";
echo $last->data->CP423172129GR->locations[0]->description."<br>";

and this is the JSON

{
  "success": true,
  "data": {
    "CP423172129GR": {
      "found": true,
      "courier_name": "ELTA",
      "courier_icon": "https://i.imgur.com/6FU9iW7.png",
      "locations": [
        {
          "datetime": "2024-06-03T11:55:00+03:00",
          "location": "ΣΟΛΩΝΟΣ (ΑΘ 56)",
          "description": "Παραλαβή αποστολής"
        },
        {
          "datetime": "2024-06-03T12:31:00+03:00",
          "location": "ΣΟΛΩΝΟΣ (ΑΘ 56)",
          "description": "Αποστολή βρίσκεται σε στάδιο μεταφοράς"
        },
        {
          "datetime": "2024-06-03T23:58:00+03:00",
          "location": "Κ.Δ. ΔΕΜΑΤΩΝ ΑΘΗΝΑΣ",
          "description": "Άφιξη σε"
        },
        {
          "datetime": "2024-06-04T01:58:00+03:00",
          "location": "Κ.Δ. ΔΕΜΑΤΩΝ ΑΘΗΝΑΣ",
          "description": "Αποστολή βρίσκεται σε στάδιο μεταφοράς"
        }
      ],
      "delivered": false
    }
  },
  "error": {
    "code": 200,
    "message": ""
  }
}

Question: How can I display the LAST nested values, which are dynamically updated? I tried with this:

echo $last->data->CP423172129GR->locations[-1]->location."<br>";

suggested by a post somewhere, but returns nothing.

………………….