Pear Class Call related issues

Pear Class Call problem
Pear installed with the class, the default installation path, the call found in each class require_once (' xx '), ' xx ' does not exist in the specified directory, that is, the path is inconsistent, so call this class will be an error, why this? Do you want to go to the source of the installed class to modify the path of the calling class? Or is it another reason?

------Solution--------------------
When Include_path is not set in php.ini, the Pear installation directory is included in the Include_path
If you specify include_path and you want to use pear, you should attach the Pear installation directory to include_path

------Solution--------------------
Then you call the full path, such as require ("d:\x\xx\1.php");
Or first look at the results of Echo dirname (__file__),
Or use Get_include_path to confirm what the current inclusion path is

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