What is the purpose of the php array_unique function?

array_unique is a function in PHP that removes duplicate elements from an array and returns a new array containing only unique elements from the original array.

Specifically, the array_unique function will go through the given array, keeping only one instance of duplicate elements and rearranging the unique elements in their original order to form a new array. Duplicate elements will only appear once in the new array.

Here is the syntax for the array_unique function:

array_unique(array $array, int $sort_flags = SORT_STRING): array

Explanation of parameters:

1. $array: the array to be processed.
2. $sort_flags (optional): Specifies the sorting criteria. The default option is SORT_STRING, which sorts the elements as strings. Other options include SORT_REGULAR, SORT_NUMERIC, SORT_LOCALE_STRING, etc.

Here is an example demonstrating how to use the array_unique function:

$numbers = [1, 2, 3, 2, 4, 1, 5];
$uniqueNumbers = array_unique($numbers);

print_r($uniqueNumbers);

Output result:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [4] => 4
    [6] => 5
)

It can be seen that the duplicate elements in the original array have been removed, resulting in a new array containing only unique elements.