User function construct user.class
First of all I recommend you to setup a local webserver to test your php code, if you have not done so jet (I assume you haven't tried your code, since your asking if it's going to work).

Secondly you should abandon mysqli for PDO. Read PHP Database Access: Are You Doing It Correctly?

Also, why are you calling the parent's constructor when the user class has no parent (eg. the class does not extend another class)?