About getting the root directory workaround

About getting the root directory
I think $_server[' document_root ' can
How did someone use this method?
Define (' _music_root_ ', str_replace (' \ \ ', '/', substr (DirName (__file__), 0,-3)));

------Solution--------------------
$_server[' document_root ') needs to be defined in the server configuration file, and the second method is not determined if there is a configuration permission.
------Solution--------------------
Yes, in most cases $_server[' document_root ' will do.
However, you should note that $_server[' document_root ' in some server configurations is not a value, or incorrect
Also $_server[' document_root ' does not correctly reflect the root of the project when your project is placed in a subdirectory

So it can be understood that:
$_server[' Document_root ' is the root path of the web site
Define (' _music_root_ ', str_replace (' \ \ ', '/', substr (DirName (__file__), 0,-3)));
is the root path of the project
------Solution--------------------
Key in the last-3 you can try not to lose, or-5
You just output the address and you'll see.
This is put in your configuration file in a code, get the absolute path of the file, minus a few is to remove the tail folder name, if you do not put in the root, the root, the other place calls are right

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