Detailed explanation of dirname(__FILE__)

__FILE__ represents the absolute path of the current file including the file name, dirname(__FILE__) represents the absolute path of the current file, basename(__FILE__) represents the file name of the current file, dirname(__FILE__)."/f/".basename (__FILE__) means a file with the file name dirname (__FILE__) in the f directory in the directory where the current file is located. require means including the file into this file.

The following is a detailed explanation:

1) The dirname(__FILE___) function returns the path where the script is located.

For example, the file b.php contains the following content:

<?php
$basedir = dirname(__FILE__);
?>

If b.php is referenced by the a.php file require or include in other directories.
The content of the variable $basedir is still the path to the folder where b.php is located.
Instead of changing to the directory where the a.php file is located.

2) dirname(__FILE__) generally returns a directory structure from the current directory where the file is located to the system root directory.

The current file name will not be returned.
dirname(__FILE__) may also return one. (current directory)
[The reason is that the b.php file is in http.conf or the default WEB directory of the PHP configuration development environment.
For example, WEB_ROOT is: "C :/root/www/".]
b.php file path is: "C:/root/www/b.php".

3) Usage tips,

If you repeat it once, you can move the directory up a level:

For example: $d = dirname(dirname(__FILE__));

In fact, it is to give a directory as a parameter to dirname(). Because dirname() returns the last directory without \\ or /
, when it is used repeatedly, it can be considered that dirname() treats the lowest directory as a file name. Return to
the upper-level directory of the current directory as usual. Repeat this to get its upper-level directory.

4) Include the file that gets the upper-level directory

include (dirname(__FILE__).''/../filename

The difference between dirname(__FILE__) and dirname(dirname(__FILE__)) in php

dirname (dirname(__FILE__));
Assume __FILE__ is/home/web/config/config.php
The output of the above method is/home/web

dirname(dirname(__FILE__)) ; What you get is the name of the directory above the file

dirname(__FILE__); What you get is the name of the directory where the file is located

Script Home editor's note: In fact, it is usedPHP’s dirname() function and __FILE__

Definition and usage
dirname() function returns the directory part of the path

Syntax

dirname(path). )

Example

<?php
echo dirname("c:/testweb/home.php");
echo dirname("/testweb/home.php");
?>

c:/testweb

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Detailed explanation of dirname, realpath, __FILE__ functions related to PHP paths

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