php 祛除重复

<?php
$array = array("apple", "banana", "apple", "orange", "banana", "banana");
$unique_array = array_unique($array);
print_r($unique_array);
?>

<?php
$array = array("apple", "banana", "apple", "orange", "banana", "banana");
$unique_array = array_keys(array_flip($array));
print_r($unique_array);
?>

<?php
$array = array("apple", "banana", "apple", "orange", "banana", "banana");
$unique_array = array();
foreach ($array as $value) {
    if (!in_array($value, $unique_array)) {
        $unique_array[] = $value;
    }
}
print_r($unique_array);
?>

<?php
$array = array("apple", "banana", array("a", "b"), array("a", "b"));
$unique_array = array_map('serialize', $array);
$unique_array = array_unique($unique_array);
$unique_array = array_map('unserialize', $unique_array);
print_r($unique_array);
?>