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.