The PHP array_udiff() function compares the values of two or more arrays, and returns an array of entries from array1 not in the other array(s).

The PHP array_udiff_assoc() function compares the keys/values of two or more arrays, and returns an array of entries from array1 not in the other array(s).

The PHP array_udiff_uassoc() function compares the keys/values of two or more arrays, and returns the entries from array1 not in the other array(s).

The PHP array_uintersect() function compares the values of two or more arrays, and returns entries from array1 that exist in the other array(s).

The PHP array_uintersect_assoc() function compares the keys/values of two or more arrays, and returns entries from array1 that exist in the other array(s).

The PHP array_uintersect_uassoc() function compares the keys/values of two or more arrays, & returns entries from array1 that exist in the other array(s).

The PHP array_unique() function removes duplicate values (the first appearance will be kept) from an array.

The PHP array_unshift() function inserts new elements to the beginning of an array. Numeric keys will start at 0. String keys will remain the same.

The PHP array_values() function returns an array containing all the values of an array.

The PHP array_walk() function runs each array element in a user-defined function with the array’s keys and values as parameters in the function.

The PHP array_walk_recursive() function runs each array element in a user-defined function with the array’s keys and values as parameters in the function.

The PHP arsort() function sorts an associative array in descending order, according to the value.

The PHP asort() function sorts an associative array in ascending order, according to the value.

The PHP compact() function creates an array from variables and their values. Any strings that does not match variable names will be skipped.

The PHP count() function returns the number of elements in an array.

The PHP current() function returns the value of the current element (every array has an internal pointer to the “current” element) in an array.

The PHP end() function moves the internal pointer to the last element in the array and outputs that element.

The PHP extract() function uses array keys as variable names and values as variable values to import variables into the local symbol table from an array.

The PHP in_array() function searches an array for a specific value.

The PHP key() function returns the element key from the current internal pointer position and FALSE if there is an error.