init.php file PHP summary of methods to obtain the parent directory of the current file

Method 1: First get the length of the folder where the current file is located, and then use substr to intercept the length:

Copy the code The code is as follows:

$dirName = str_replace("\", "/", dirname (__FILE__));
$dirNameLength = strlen($dirName);
$currentDirNameLength = $dirNameLength - strrpos($dirName,"/"); //Get the length of the folder where the current file is located!
$parentDirName = substr($dirName,0,-$currentDirNameLength); //If the third parameter is a negative number, it means that [the absolute value of the parameter] characters will be intercepted from the back.

Method 2: Treat the folder where the current file is located as a file (the folder is actually a special file, everything is a file!!), just use dirname to nest the dirname once:

 $parentDirName = dirname(dirname(__FILE__));

From It can be seen from the above: a deep understanding of things can greatly improve the quality of the code!

Attached: PHP gets the path or directory implementation

PHP gets the directory and the method through magic variables; through super global variables; through related functions, etc.:

<&#63;php
/**
 * PHP获取路径或目录实现
 */
 
//魔术变量，获取当前文件的绝对路径
echo "__FILE__: ========> ".__FILE__; 
echo '<br/>';
 
//魔术变量，获取当前脚本的目录
echo "__DIR__: ========> ".__DIR__;
echo '<br/>';
 
//dirname返回路径的目录部分,dirname(__FILE__)相当于__DIR__
echo "dirname(__FILE__): ========> ".dirname(__FILE__);
echo '<br/>';
 
//$_SERVER['PHP_SELF']和$_SERVER['SCRIPT_NAME']的结果一般相同，他们都是获取当前脚本的文件名
//只有当php以cgi方式运行时有区别，但是现在几乎找不到以cgi方式运行php了
echo '$_SERVER["PHP_SELF"]: ========> '.$_SERVER['PHP_SELF'];
echo '<br/>';
 
echo '$_SERVER["SCRIPT_NAME"]: ========> '.$_SERVER['SCRIPT_NAME'];
echo '<br/>';
 
//当前执行脚本的绝对路径。记住，在CLI方式运行php是获取不到的
echo '$_SERVER["SCRIPT_FILENAME"]: ========> '.$_SERVER['SCRIPT_FILENAME'];
echo '<br/>';
 
//当前运行脚本所在的文档根目录。在服务器配置文件中定义。
echo '$_SERVER["DOCUMENT_ROOT"]: ========> '.$_SERVER['DOCUMENT_ROOT'];
echo '<br>';
 
//getcwd()返回当前工作目录
echo "getcwd(): ========> ".getcwd();
echo '<br>';

The above introduces the init.php file and a summary of PHP methods to obtain the parent directory of the current file, including the content of the init.php file. I hope it will be helpful to friends who are interested in PHP tutorials.