isset vs empty vs is_null

Question

I\'m trying to write a script that when a user uploads a file and does not enter a name an error is returned. I\'ve tried using is_null, empty, and isset and they all do not

Answer 1

1. isset() — Determine if a variable is set and not NULL

2. empty() - Determine if a variable is empty.

3. is_null() - Determine if a variable is null