The PHP array_key_exists() function checks an array for a specified key, and returns “true” if the key exists and “false” if the key does not exist.

The PHP array_keys() function returns an array containing the keys.

The PHP array_map() function sends each value of an array to a user-made function, and returns an array with new values, given by the user-made function.

The PHP array_merge() function merges one or more arrays into one array. If two or more elements have the same key, the last one overrides the others.

The PHP array_merge_recursive() function merges one or more arrays into one array. If two or more elements have the same key, a nested array is created.

The PHP array_multisort() function returns a sorted array from one or more arrays.

The PHP array_pad() function inserts a specified number of elements, with a specified value, to an array.

The PHP array_pop() function deletes the last element of an array.

The PHP array_product() function calculates and returns the product of an array.

The PHP array_push() function inserts one or more elements to the end of an array, using numeric keys for the new items even if the array uses string keys.

The PHP array_rand() function returns a random key from the function, or an array of random keys if you specify the return of more than one key.

The PHP array_reduce() function sends the values in an array to a user-defined function, and returns a string.

The PHP array_replace() function replaces the values of the first array with the values from following arrays.

The PHP array_replace_recursive() function replaces the values of the first array with the values from following arrays recursively.

The PHP array_reverse() function returns an array in the reverse order.

The PHP array_search() function searches an array for a value and returns the key.

The PHP array_shift() function removes the first element from an array, and returns the value of the removed element.

The PHP array_slice() function returns selected parts of an array.

The PHP array_splice() function removes selected elements from an array and replaces it with new elements.

The PHP array_sum() function returns the sum of all the values in the array.