|What is the data source of $UserName and $PassWord? Are you using a form, reading data from a cookie, or maybe static assignment? If the former, then you need to use one of the globals, $_COOKIE, $_POST or $_GET to acquire the data.|
You might also want to use an identity test instead of a comparison test - $UserName === $UNEqual
What do you mean by C++? Do you mean executing a binary? If so, then your host would need to allow it. I've used C before, but not C++; here's a resource on html and c++ that *may* help you out.