PHP connection error with Mysql via XAMPP

Question

The xamp is active, but this message appears:

Fatal error: Uncaught Error: Call to Undefined Function mysqli_connect() in C: wamp64T www projects feira_ita BD conexao.php:10 Stack trace: #0 C: wamp64T www projects feira_ita valida.php(3): include_once() #1 {main} thrown in C: wamp64T www projects feira_ita BD connectionon.php online 10

$servidor = "localhost";
$usuario = "root";
$senha = "";
$dbname = "db";

//Criar a conexao
$conn = mysqli_connect($servidor, $usuario, $senha, $dbname) or die("Falha na conexao: " . mysqli_connect_error());