Dirname (_ file _)

For example, the current file is placed under (d: \ www \) and the file name is test. php.
TestedCodeAs follows:

1. <? PHP
2. Echo _ file _; // obtain the absolute address of the current file. Result: D: \ www \ test. php
3. Echo dirname (_ file _); // obtain the absolute directory of the current file. Result: D: \ www \
4. Echo dirname (_ file _); // obtain the name of the previous directory of the current file. Result: D :\
5. ?>

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 ');