Best method for creating absolute path in PHP? (See 3 methods listed inside)

问题

I can create paths with no problem, but I want to know which of these 3 methods is the most rock solid and reliable and will work on the most servers.

Right now I am using method 1 in my script and some users are having path issues. I just want the method that will work on any version of php and almost any server config.

1.  <?php echo $_SERVER['DOCUMENT_ROOT']; ?>

2.  <?php echo getcwd(); ?>

3.  <?php echo dirname(__FILE__); ?>

Thank you so much for any expertise you can provide about this!

回答1:

dirname(__FILE__) will always work, regardless of platform or webserver. DOCUMENT_ROOT may work differently between server configurations (Apache vs IIS vs Lighttpd vs nginex). cwd shows the selected working directory which may or may not be correct (you can change it in the script). So I'd suggest dirname(__FILE__)

回答2:

• $_SERVER array holds user data and therefore can't be trusted is dependent on the platform (webserver).

• The current working directory may depend on the entry point of the request. Consider this example (CLI):

  cd ~/mypath/mypath2
  php myscript.php
  cd ~/mypath
  php mypath/myscript.php
  

• IMHO the securest solution is to use dirname(__FILE__) or __DIR__ (since PHP 5.3) as the file path will always be the same (relative to your projects structure).

来源：https://stackoverflow.com/questions/2893088/best-method-for-creating-absolute-path-in-php-see-3-methods-listed-inside