产品在php数组中出现两次

$array_with_duplicates = ['apple', 'banana', 'apple', 'orange'];
$array_without_duplicates = array_unique($array_with_duplicates);
print_r($array_without_duplicates);

$array_with_duplicates = ['apple', 'banana', 'apple', 'orange'];
$unique_array = [];

foreach ($array_with_duplicates as $item) {
    if (!in_array($item, $unique_array)) {
        $unique_array[] = $item;
    }
}

print_r($unique_array);

$array_with_duplicates = ['apple', 'banana', 'apple', 'orange'];
$unique_array = array_flip($array_with_duplicates);
$unique_array = array_keys($unique_array);

print_r($unique_array);