(PHP 4 >= 4.3.0, PHP 5, PHP 7) Computes the difference of arrays with additional index check

(PHP 4, PHP 5, PHP 7) Sort an array with a user-defined comparison function and maintain index association

(PHP 4, PHP 5, PHP 7) Return all the keys or a subset of the keys of an array

(PHP 4, PHP 5, PHP 7) Prepend one or more elements to the beginning of an array

(PHP 4 >= 4.0.1, PHP 5, PHP 7) Removes duplicate values from an array

(PHP 4 >= 4.0.4, PHP 5, PHP 7) Calculate the sum of values in an array

(PHP 5 >= 5.5.0, PHP 7) Return the values from a single column in the input array

(PHP 5 >= 5.2.0, PHP 7) Fill an array with values, specifying keys

(PHP 4 >= 4.0.5, PHP 5, PHP 7) Searches the array for a given value and returns the corresponding key if

(PHP 4, PHP 5, PHP 7) Shift an element off the beginning of array