有两种方法来设置php的include_path

一：修改php.ini文件中的include_path项。

例：include_path = .:/usr/local/lib/php:./include

二：使用ini_set方法。

例：ini_set("include_path", ".:../:./include:../include");

How do I set PHP include_path?

  There are at least 2 ways you can set your PHP include_path.

1. Edit your /etc/php.ini file. Inside that file is a directive section for "Paths and Directories." By default it is set to ".:/usr/local/lib/php". You can change that value to whatever you like or add to (or eliminate) the default like this:
   
   
   include_path = .:/usr/local/lib/php:./include
   
   The above must be entered all on one line, with no linebreaks. The above will cause php scripts to search for a directory named "include", and will look for it under the current directory of the running script in addition to the default, which is to first search the current directory and then search the /usr/local/lib/php directory (which is a system directory that is not writeable by you and is reserved for things like PEAR).
   
   The format of the include_path variable is a list of directories separated with a colon. A "." (a period) in the include path means the current directory, and allows for relative includes. More information is available here.
   
   
2. Use the function ini_set(). For example if you wanted to set your PHP include_path to ".:../:./include:../include" then you would do this in your PHP code:
   

   ini_set("include_path", ".:../:./include:../include");

   You can also use ini_set() to affect other PHP settings like