Predefined Constants

The constants below are always available as part of the PHP core.

CASE_LOWER (integer)

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 (integer)

CASE_UPPER is used with array_change_key_case() and is used to convert array keys to upper case.

Sorting order flags:

SORT_ASC (integer)

SORT_ASC is used with array_multisort() to sort in ascending order.

SORT_DESC (integer)

SORT_DESC is used with array_multisort() to sort in descending order.

Sorting type flags: used by various sort functions

SORT_REGULAR (integer)

SORT_REGULAR is used to compare items normally.

SORT_NUMERIC (integer)

SORT_NUMERIC is used to compare items numerically.

SORT_STRING (integer)

SORT_STRING is used to compare items as strings.

SORT_LOCALE_STRING (integer)

SORT_LOCALE_STRING is used to compare items as strings, based on the current locale. Added in PHP 4.4.0 and 5.0.2.

SORT_NATURAL (integer)

SORT_NATURAL is used to compare items as strings using "natural ordering" like natsort(). Added in PHP 5.4.0.

SORT_FLAG_CASE (integer)

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.

COUNT_NORMAL (integer)

COUNT_RECURSIVE (integer)

EXTR_OVERWRITE (integer)

EXTR_SKIP (integer)

EXTR_PREFIX_SAME (integer)

EXTR_PREFIX_ALL (integer)

EXTR_PREFIX_INVALID (integer)

EXTR_PREFIX_IF_EXISTS (integer)

EXTR_IF_EXISTS (integer)

EXTR_REFS (integer)