Hi I have trouble with this code. Why it doesn't work?

Question

Sending data to the server.
https://code.sololearn.com/wmZ4W1JP5Y4v/?ref=app

Answer 1

You cannot work with php form in Solo-Learn

Answer 2

A͢J I didn't know. Thanks
Is it because of security or what?

Answer 3

Is better you use empty() function for this