在本文中我們使用 print_r 來印出 array 的結構，方便驗證我們的 code

$arr = ['a', 'b', 'c'];
print_r($arr);

output

Array
(
    [0] => a
    [1] => b
    [2] => c
)

sum

就只是取 value 的 總和

$nums = [4, 3, 5, 2, 1];
$sum = array_sum($nums);
print_r($sum);

output

15

count

就只是取 array 的個數

$nums = [4, 3, 5, 2, 1];
$sum = count($nums);
print_r($sum);

output

5

array_column

將 array 中指定的 key 當中的 value 取出成一個新的 array

$records = [
    ["id" => 1, "name" => "dad", "age" => 34],
    ["id" => 2, "name" => "son", "age" => 14],
    ["id" => 3, "name" => "mom", "age" => 28],
];
$column = array_column($records, 'name');
print_r($column);

output

Array
(
    [0] => dad
    [1] => son
    [2] => mom
)

array_keys

將 array 中的 key 取出成一個新的 array

$records = ["id" => 1, "name" => "dad", "age" => 34];
$keys = array_keys($records);
print_r($keys);

output

Array
(
    [0] => id
    [1] => name
    [2] => age
)

array_values

將 array 中的 value 取出成一個新的 array

$records = ["id" => 1, "name" => "dad", "age" => 34];
$values = array_values($records);
print_r($values);

output

Array
(
    [0] => 1
    [1] => dad
    [2] => 34
)

array_map

根據當前的 array 資料產生新的 array

$records = [
    ["id" => 1, "name" => "dad", "age" => 34],
    ["id" => 2, "name" => "son", "age" => 14],
    ["id" => 3, "name" => "mom", "age" => 28],
];
$map = array_map(
    function($item) {
        $item['rank'] = $item['id'] * 5;
        return $item;
    }, 
    $records
);
print_r($map);

output

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => dad
            [age] => 34
            [rank] => 5
        )

    [1] => Array
        (
            [id] => 2
            [name] => son
            [age] => 14
            [rank] => 10
        )

    [2] => Array
        (
            [id] => 3
            [name] => mom
            [age] => 28
            [rank] => 15
        )

)

array_filter

根據當前的 array 進行篩選

$records = [
    ["id" => 1, "name" => "dad", "age" => 34],
    ["id" => 2, "name" => "son", "age" => 14],
    ["id" => 3, "name" => "mom", "age" => 28],
];
$filter = array_filter(
    $records,
    function($item) {
        return $item['age'] > 25;
    }
);
print_r($filter);

output

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => dad
            [age] => 34
        )

    [2] => Array
        (
            [id] => 3
            [name] => mom
            [age] => 28
        )

)

array_push

新增一個 item 於 array 末端

$nums = [5, 6, 7];
array_push($nums, 8);
print_r($nums);

output

Array
(
    [0] => 5
    [1] => 6
    [2] => 7
    [3] => 8
)

array_pop

移除 array 最末端的 item

$nums = [5, 6, 7];
array_pop($nums);
print_r($nums);

output

Array
(
    [0] => 5
    [1] => 6
)

array_merge

進行 array 的 合併和 value 複寫

Example 1

$arr1 = ['a', 'b', 'c'];
$arr2 = ['d', 'e', 'f'];
$arr3 = array_merge($arr1, $arr2);
print_r($arr3);

output

Array
(
    [0] => a
    [1] => b
    [2] => c
    [3] => d
    [4] => e
    [5] => f
)

Example 2

$arr = ['id' => 1, "name" => "wang"];
$arr2 = array_merge($arr, ["name" => "aki", "age" => 34]);
print_r($arr2);

output

Array
(
    [id] => 1
    [name] => aki
    [age] => 34
)

sort

依照 value 由小到大排序

$nums = [4, 3, 5, 6, 2, 1];
sort($nums);
print_r($nums);

output

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

asort

依照 value 由小到大排序，但 key 保留原本的排序

$nums = [4, 3, 5, 6, 2, 1];
asort($nums);
print_r($nums);

註：value 1 在 asort 前在 index 5 的位置，因此 asort 完 key 為 5

註：value 2 在 asort 前在 index 4 的位置，因此 asort 完 key 為 4

output

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

ksort

依照 key 由小到大排序

$nums = ["d" => 4, "c" => 3, "e" => 5, "f" => 6, "b" => 2, "a" => 1];
ksort($nums);
print_r($nums);

output

Array
(
    [a] => 1
    [b] => 2
    [c] => 3
    [d] => 4
    [e] => 5
    [f] => 6
)

array_search

找出 value 在 array 中的 index，與 Java 中的 indexOf 功能相同

$arr = ['a', 'b', 'c'];
$index = array_search('b', $arr);
print_r($index);

output

1

array_unique

去除重複的 value

$arr = ['⬆', '⬆', '⬇', '⬇', '⬅', '⮕', '⬅', '⮕', 'B', 'A'];
$arr2 = array_unique($arr);
print_r($arr2);

output

Array
(
    [0] => ⬆
    [2] => ⬇
    [4] => ⬅
    [5] => ⮕
    [8] => B
    [9] => A
)