php man page for spl_autoload_extensions

SPL_AUTOLOAD_EXTENSIONS(3)						 1						SPL_AUTOLOAD_EXTENSIONS(3)

spl_autoload_extensions - Register and return default file extensions for spl_autoload

SYNOPSIS
       string spl_autoload_extensions ([string	$file_extensions])

DESCRIPTION
	This function can modify and check the file extensions that the built in __autoload(3) fallback function spl_autoload(3) will be using.

PARAMETERS
	      o $file_extensions
		-  When  calling without an argument, it simply returns the current list of extensions each separated by comma. To modify the list
		of file extensions, simply invoke the functions with the new list of file extensions to use in a single string	with  each  exten-
		sions separated by comma.

RETURN VALUES
	A comma delimited list of default file extensions for spl_autoload(3).

PHP Documentation Group 												SPL_AUTOLOAD_EXTENSIONS(3)