Source: http://my.oschina.net/rain21/blog/470986
PHP Output page All variables
Print_r (Get_defined_vars ());
This function returns a multidimensional array that contains a list of all defined variables, including environment variables, server variables, and user-defined variables.
get all functions that have already been defined
Get_defined_functions ()
get all the available modules
Get_loaded_extensions ()
gets the available functions for the specified module
Get_extension_funcs ()
This function returns all available functions for the specified module. The parameter passed in (module name) must be lowercase
get the name of the associative array all the constants and their values -(PHP 4 >= 4.1.0, PHP 5)
Get_defined_constants ()
get_declared_classes (PHP 4, PHP 5)-Gets an array of the names of the defined classes
Get_declared_classes ()
get_included_files () (or get_require_files) (PHP 4, PHP 5)-Gets an array of the names of the defined classes
Get_included_files ()
PHP Output page All variables