Silly php script path, silly php script

Silly php script path, silly php script

If you don't need to talk about it, you can directly raise the question today. To be precise, you can tell the difference between multiple similar global variable constants related to the current script information.

First paste the Code:

<? Phpecho $ _ SERVER ['php _ SELF ']; echo " 
The address in the browser is http: // localhost/test/test4.php? A = 3 localhost is the root directory.
 
Now, what I have carefully read is a bit confusing.
 
I don't need to explain the results. I believe many people can understand the results at a glance.