Php dirname (_ FILE _) to obtain the absolute path of the current FILE

For example, the current file is placed under (d: \ www \) and the file name is test. php.
The test code is as follows:
Copy codeThe Code is as follows:
<? Php
Echo _ FILE _; // obtain the absolute address of the current FILE. Result: D: \ www \ test. php
Echo dirname (_ FILE _); // obtain the absolute directory of the current FILE. Result: D: \ www \
Echo dirname (_ FILE _); // obtain the name of the previous directory of the current FILE. Result: D :\
?>

Usage tips,
Dirname (_ FILE _) obtains the absolute path of the current FILE, that is, the fastest search speed compared to the relative path.
If you repeat the command, you can raise the directory to a higher level:
For example: $ d = dirname (_ FILE __));
In fact, a directory is used as a parameter to dirname (), because the last directory returned by dirname () does not contain \ or/
Therefore, we can think that dirname () treats the bottom directory as a file name.
The upper-level directory of the current directory.

Include the files to obtain the upper-level directory
Include (dirname (_ FILE _). '/../filename. php ');

The path of _ FILE _ is the FILE where the current code is located.

Dirname (_ FILE _); the directory name at the top of the FILE is obtained.

Dirname (_ FILE _); the directory name of the FILE's layer is obtained.