&reftitle.constants; &extension.constants.core; CASE_LOWER (int) CASE_LOWER is used with array_change_key_case and is used to convert array keys to lower case. This is also the default case for array_change_key_case. CASE_UPPER (int) CASE_UPPER is used with array_change_key_case and is used to convert array keys to upper case. Sorting order flags: SORT_ASC (int) SORT_ASC is used with array_multisort to sort in ascending order. SORT_DESC (int) SORT_DESC is used with array_multisort to sort in descending order. Sorting type flags: used by various sort functions SORT_REGULAR (int) SORT_REGULAR is used to compare items normally. SORT_NUMERIC (int) SORT_NUMERIC is used to compare items numerically. SORT_STRING (int) SORT_STRING is used to compare items as strings. SORT_LOCALE_STRING (int) SORT_LOCALE_STRING is used to compare items as strings, based on the current locale. Added in PHP 5.0.2. SORT_NATURAL (int) SORT_NATURAL is used to compare items as strings using "natural ordering" like natsort. Added in PHP 5.4.0. SORT_FLAG_CASE (int) SORT_FLAG_CASE can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively. Added in PHP 5.4.0. Filter flags: ARRAY_FILTER_USE_KEY (int) ARRAY_FILTER_USE_KEY is used with array_filter to pass each key as the first argument to the given callback function. Added in PHP 5.6.0. ARRAY_FILTER_USE_BOTH (int) ARRAY_FILTER_USE_BOTH is used with array_filter to pass both value and key to the given callback function. Added in PHP 5.6.0. COUNT_NORMAL (int) COUNT_RECURSIVE (int) EXTR_OVERWRITE (int) EXTR_SKIP (int) EXTR_PREFIX_SAME (int) EXTR_PREFIX_ALL (int) EXTR_PREFIX_INVALID (int) EXTR_PREFIX_IF_EXISTS (int) EXTR_IF_EXISTS (int) EXTR_REFS (int)