The difference between .. and . in php path

The difference between .. and . in the php path is: 1. ".." indicates the upper-level directory. When ".." is used in the file path, it will tell the operating system or server to return to the previous directory. level directory; 2. "." indicates the current directory. When "." is used in the file path, it indicates the current directory.

Operating system for this tutorial: Windows 10 system, php8.1.3 version, Dell G3 computer.

In PHP, .. and . are special symbols used to represent file paths.

• ..: Indicates the upper-level directory. When .. is used in a file path, it tells the operating system or server to go back to the previous directory.

• .: Indicates the current directory. When . is used in a file path, it represents the current directory.

The following is an example that demonstrates the use of .. and .:

// 当前文件路径：/var/www/html/example/index.php
echo realpath('../'); // 输出：/var/www/html
echo realpath('.');   // 输出：/var/www/html/example

In the above example, the realpath() function is used to obtain the absolute value of the specified path path. We can see that ../ returns the absolute path of the upper-level directory /var/www/html, and . returns the absolute path of the current directory /var/www/html/example.

It should be noted that .. and . only represent symbols. How to handle these symbols depends on the operating system and file system. When dealing with file paths, it is recommended to use absolute paths or build new paths based on a known path to avoid path problems and security risks.

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