PHP implode function error, does not include implode string

try something like

$currencies = [] // Create an empty array
foreach($stocks->currency as $currency)
{
  $d1 = $currency->cost;
  $d2 = $currency->currency->name;
  $currencies[] = ' ' . $d1 . ' ' . $d2; // Add a new value to your array
}
echo implode("or", $currencies); // implode the full array and separate the values with "or"