ftisland hello hello PHP gets the __FILE__ constant of the root directory

1. PHP's __FILE__ constant (how to get the root directory)
dirname(__FILE___) function returns the path where the script is located.
For example, the file b.php contains the following content:
$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 becoming the directory where the a.php file is located.
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.
For example, WEB_ROOT is: "C:/root/www/ ".]
The path of the b.php file is: "C:/root/www/b.php". Usage tips, if you repeat it once, you can move the directory up a level:
For example: $d = dirname(dirname( __FILE__));
In fact, a directory is given as a parameter to dirname(). Because dirname() returns the last directory without \＼ or /
, so when it is used repeatedly, it can be considered that dirname() treats the lowest directory as a file name. Return to the upper-level directory of the current directory as usual. Repeat this to get its upper-level directory. Include the file in the upper-level directory include(dirname(__FILE__).'/../filename.php');2. How to use PHP files and html files together if($reguser != ""){
echo"Submit Photo
";
echo"Log Out";
}else{
echo"Login";
}
?>
The above introduces ftisland hello hello PHP to get the __FILE__ constant of the root directory, including the content of ftisland hello hello. I hope it will be helpful to friends who are interested in PHP tutorials.