$_POST["emailAdd"] = "johno@email.com";
    $_POST["fullName"] = "John O";
    // $_POST["accountNum"] = "ZAP AND 1=1 --";
    // $_POST["accountNum"] = "ZAP OR 1=1 --";
    // $_POST["accountNum"] = "234-123456-123";

    $upTwo = realpath(__DIR__ . '/../..');
    require_once $upTwo . '/vendor/autoload.php';
    include $upTwo . '/src/helper.php';

    $errors = array();
    $userData = array();
    $inputArray = array();
    $config = new CONFIGConfig();

    // sanitise user data
    if (empty($_POST['fullName'])) {
        $errors['fullName'] = '- Please input your Full Name as per Passport';
    } else {
        $fullName = filter_var($_POST['fullName'], FILTER_SANITIZE_STRING);
        array_push($inputArray, $fullName);
    }

    if (empty($_POST['emailAdd'])) {
        $errors['emailAdd'] = '- Please input your Email address';
    } else {
        if (!filter_var($_POST['emailAdd'], FILTER_VALIDATE_EMAIL)) {
            $errors['emailAdd'] = '- Please input your Email address';
        } else {
            $email = filter_var($_POST['emailAdd'], FILTER_SANITIZE_EMAIL);
            array_push($inputArray, $email);
        }
    }

    if (empty($_POST['accountNum'])) {
        $errors['accountNum'] = '- Please input your Account Number';
    } else {
        // regex looks for exact 14 character combination of 3 digits, one dash, 6 digits, one dash and 3 digits
        if (!filter_var($_POST['accountNum'], FILTER_VALIDATE_REGEXP, array("options"=>array("regexp"=>"/^d{3}-d{6}-d{3}$/")))) {
            $errors['accountNum'] = '- Please enter correct account number';
        } else {
            $accountNum = filter_var($_POST['accountNum'], FILTER_VALIDATE_REGEXP, array("options"=>array("regexp"=>"/^d{3}-d{6}-d{3}$/")));
            array_push($inputArray, $accountNum);
        }
    }

    // save user details in db
    if (empty($errors)) {

        try {

            // save user details in db if not sanitisation errors
            $dbh = new PDO("mysql:host=" . $config::DB_HOST . ";dbname=" . $config::DB_NAME . "", $config::DB_USER, $config::DB_PASSWORD);

            $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

            $stmt = $dbh->prepare("INSERT INTO " . $config::DB_TABLE . "(full_name, email_address, account_number) VALUES (?, ?, ?)");
            $stmt->bindParam(1, $inputArray[0]);
            $stmt->bindParam(2, $inputArray[1]);
            $stmt->bindParam(3, $inputArray[2]);

            $response = $stmt->execute(); // $response variable added for debugging purposes
            var_dump($response); // var_dump() added for debugging purposes

            $userData["lastId"] = $dbh->lastInsertId();

        } catch (Exception $e) {

            logError($e->getMessage(), $e->getFile(), $e->getLine());
            $errors['dbInsert'] = $e->getMessage();
            throw new Exception($e->getMessage() . " | File: " . $e->getFile() . " | Failure on line: " . $e->getLine());

        }

    }

johno:php johno$ php process.php
array(1) {
  ["accountNum"]=>
  string(37) "- Please enter correct account number"
}
array(2) {
  [0]=>
  string(6) "John O"
  [1]=>
  string(15) "johno@email.com"
}
johno:php johno$ php process.php
array(1) {
  ["accountNum"]=>
  string(37) "- Please enter correct account number"
}
array(2) {
  [0]=>
  string(6) "John O"
  [1]=>
  string(15) "johno@email.com"
}
johno:php johno$ php process.php
array(0) {
}
array(3) {
  [0]=>
  string(6) "John O"
  [1]=>
  string(15) "johno@email.com"
  [2]=>
  string(14) "234-123456-123"
}
bool(true)