array_unique()

array_unique() — Removes duplicate values from an array.

Built-in function of PHP 8.5. The manual lists it as available in PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

Takes an input array and returns a new array without duplicate values.

Signature

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

Parameters

ParameterTypeWhat it takes
$arrayarrayThe input array.
$flagsintThe optional second parameter flags may be used to modify the comparison behavior using these values:

Return value

Returns the filtered array.

Example

A runnable snippet:

$input = ["a" => "green", "red", "b" => "green", "blue", "red"]; $result = array_unique($input); print_r($result);

Output:

Array ( [a] => green [0] => red [1] => blue )

Changelog

VersionChange
7.2.0If flags is SORT_STRING, the returned array is built by adding the unique elements to a new array; formerly, it was a copy of array from which the non-unique elements were removed. Both hold the same elements under the same keys, but if the element with the largest integer key is among those ...

See also

array_count_values()

All PHP 8.5 built-in functions

Reference card built from the PHP manual page array_unique() (PHP documentation, CC BY 3.0). The page is generated from the manual, so the wording of the parameter and return value text follows php.net.