I have a very basic doubt about PHP, please give me some advice.

A very basic problem with PHP, please give me some advice
<?php
$upfile=$_FILES[“upfile”];
?>

Upload File

The above is the code Content, when I run the web page, I always get an error message from the $upfile=$_FILES[“upfile”]; line. What went wrong?

——Solution——————–
Well…

Actually, this is a prompt. It is an improvement of PHP after version 5.x. If you feel irritated, you can block these prompts by turning off the error prompts in php.ini. , of course I don’t recommend doing this. Therefore, such submitted value issues can be judged through isset. If it is a variable, it can be solved by initialization assignment.