Constructs an APCIterator iterator object - Справочник: PHP5.4

public APCIterator::__construct ( string $cache [, mixed $search = null [, int $format [, int $chunk_size = 100 [, int $list ]]]] )

cache: The cache type, which will be user or file.
search: A PCRE regular expression that matches against APC key names, either as a string for a single regular expression, or as an array of regular expressions. Or, optionally pass in NULL to skip the search.
format: The desired format, as configured with one ore more of the APC_ITER_* constants.
chunk_size: The chunk size. Must be a value greater than 0. The default value is 100.
list: The type to list. Either pass in APC_LIST_ACTIVE or APC_LIST_DELETED.

An APCIterator object on success, or NULL on failure.