How to use PHP __FILE__ to get the absolute path of a file_PHP tutorial

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PHP constant dirname(__file__)

__FILE__: Known as PHP magic constant, returns the full path and file name of the currently executing PHP script, including an absolute path

1) The dirname(__FILE__) function returns the path where the script is located. ​​Update network
For example, the file b.php tutorial contains the following content:
                                                                                                                echo $basedir //The absolute path to where this file is located will be printed out on the page!
?>
The test I did got the result: E:websiteothertestcms
This is equivalent to the usage of server.mappth in asp tutorial

If b.php is referenced by 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. Rather than becoming 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 a . (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

echo dirname(__FILE__); // Get the absolute directory where the current file is located, result: D:www echo dirname(dirname(__FILE__)); //Get the upper directory name of the current file, result: D:
?>
===========PHP Get absolute file path========

===========chdir() function===========

The chdir() function changes the current directory to the specified directory.

If successful, the function returns true, otherwise it returns false.

Grammar

directory required. Specifies the new current directory.
Example

//Get the current directory

echo getcwd(); echo "
";

//Change to images directory

chdir("images");

echo "
";
echo getcwd();
?> Output:

C:testwebmain

C:testwebmainimages

If successful, the function returns true, otherwise it returns false.

Grammar

directory required. Specifies the new current directory.
Example

//Get the current directory

echo getcwd(); echo "
";

//Change to images directory

chdir("images");

echo "
";
echo getcwd();
?>

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