Returns all the registered configuration options as an associative array. If the optional extension parameter is set, returns only options specific for that extension.
The returned array uses the directive name as the array key, with elements of that array being global_value (set in php.ini), local_value (perhaps set with ini_set() or .htaccess), and access (the access level). See the manual section on configuration changes for information on what access levels mean.
注: It's possible for a directive to have multiple access levels, which is why access shows the appropriate bitmask values.
See also: ini_get(), ini_restore(), ini_set(), get_loaded_extensions(), and phpinfo().