<?php

$hostname = 'localhost';
$username = 'root';
$password = '';

function testdb_connect ($hostname, $username, $password){
    $dbh= new PDO("mysql:host=$hostname;dbname=users", $username, $password);
    return $dbh;
}

try {
    $dbh = testdb_connect ($hostname, $username, $password);
    echo 'Connected to database';
} catch(PDOException $e) {
    echo $e->getMessage();
}