<br /><b>Notice</b>: Undefined variable: username in <b>G:\xampp\htdocs\Online Class Platform\students_register.php</b> on line <b>166</b><br />
There is no variable. thats the reason
function sum() {
// args looks like: array(1,2,3)
$args = func_get_args();
return array_sum($args);
}
echo sum(1,2,3); // prints 6
$name = isset($_POST['name']) ? $_POST['name'] : '';
if (isset($_POST['submit']) && $human == '4') {