function clear_input($input_data)
{
if (is_array($input_data)) {
foreach ($input_data as $key => $value) {
$output_data[$key] = clear_input($input_data[$key]);
}
} else {
if (get_magic_quotes_gpc() == 1) {
stripslashes($input_data);
}
$output_data = mysql_real_escape_string(trim($input_data));
}
return $output_data;
}
$firstname = $lastname = $email = $grade = $class = "";
$data_ok = true;
//removes space, tab and newline and avoids cross-site scripting, sql-injections etc.
function clear_input($data, $conn)
{
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
$data = mysqli_real_escape_string($conn, $data);
return $data;
}
$firstname = clear_input($_POST["firstname"], $conn);
$lastname = clear_input($_POST["lastname"], $conn);
$email = clear_input($_POST["email"], $conn);
$grade = clear_input($_POST["grade"], $conn);
$class = clear_input($_POST["class"], $conn);
//Check if a field was left empty
if (empty($firstname)) {
$data_ok = false;
echo "<div class='alert alert-warning'>Bitte gib deinen Vornamen an!</div>";
}
if (empty($lastname)) {
$data_ok = false;
echo "<div class='alert alert-warning'>Bitte gib deinen Nachnamen an!</div>";
}
if (empty($email)) {
$data_ok = false;
echo "<div class='alert alert-warning'>Bitte gib deine Mailadresse an!</div>";
} else {
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
$data_ok = false;
